Detailed description of the invention
The preferred embodiment of the technology disclosed in this specification it is described in detail in later with reference to accompanying drawing.When logical
When form of crossing distinguishes each function element, each function element will with alphabetic character, " n " (n be digital),
Or a combination thereof describes as the labelling being attached to each function element.Each when describing with distinguishing the most especially
During function element, labelling will be omitted.For accompanying drawing too.
To illustrate in the following order.
1. summary
2. the summary of display device
3. light-emitting component
4. driving method: basis
5. the object lesson of application: illustrate that the brightness caused by back-gate effect lacks phenomenon
First embodiment: basis (controls the backgate of write transistor)
Second embodiment: write pulse is coupled to backgate by capacity cell
3rd embodiment: video signal is coupled to backgate by capacity cell
4th embodiment: write pulse is coupled to backgate by buffer
5th embodiment: the example of the electronic installation of application
<summary>
First basic point below will be described.
In the structure of the present embodiment, image element circuit, display device or electronic installation include: display part
Point;Storage capacitor;For would correspond to video signal driving voltage write storage capacitor write crystalline substance
Body pipe;And driving transistor, drive display part for driving voltage based on write storage capacitor.
In image element circuit, display device, electronic installation and the side driving image element circuit (or display device)
In method, to write what the process operation of storage capacitor associated with the driving voltage that would correspond to video signal
Mode, controls the characteristic of write transistor.By to control by the way of associating with signal writing operation to write crystal
The characteristic of pipe adjusts the write capability of write transistor.Therefore, even when the level of the video signal applied
Time identical, the level of the signal of write storage capacitor also can be adjusted.Owing to adjustable write capability is to obtain
The brightness of the level of applied video signal must be corresponded to, so even imitating when the field with back-gate effect
When answering transistor to be used for signal write, it is possible to obtain video signal corresponding to being applied more reliably
The brightness of level.
Preferably, image element circuit includes Characteristics Control part, for with would correspond to driving of video signal
Galvanic electricity pressure writes the mode processing operation association of storage capacitor, controls the characteristic of described write transistor.
In order to realize " to write the process behaviour of storage capacitor with the driving voltage that would correspond to video signal
Make the mode associated, control the characteristic of write transistor ", specifically, would correspond to the driving of video signal
The write capability increasing write transistor in the period of the process of voltage write storage capacitor is sufficient for.
More specifically, preferably the process of storage capacitor is write with the driving voltage that would correspond to video signal
Beginning increase the write capability of write transistor simultaneously.I.e., especially, opening when the write capability of write transistor
When the moment of beginning signal write increases, it is thus achieved that well effect.Need not signal write process whole
Period increases the write capability of write transistor.
An aspect according to transistor characteristic, preferably writes with the driving voltage that would correspond to video signal
The beginning of the process of storage capacitor reduces the threshold voltage of write transistor simultaneously.I.e., especially, when writing
The threshold voltage of transistor is when the start time that signal writes reduces, it is thus achieved that well effect.Work as threshold value
When voltage declines, the write capability of write transistor can be increased.Need not signal write process whole time
The threshold voltage of write transistor is reduced in Duan.
Preferably, use has the transistor of the Characteristics Control terminal that can control threshold voltage as writing crystalline substance
Body pipe.In this case, the control signal controlling threshold voltage is applied to Characteristics Control terminal.
Such as, back of the body gate type thin film transistor or MOSFET(metal oxide film field-effect transistor) close
It is useful as the transistor with the Characteristics Control terminal that can control threshold voltage.Particularly preferably use
MOSFET。
When the transistor with the Characteristics Control terminal that can control threshold voltage is used as write transistor,
Can use constructed as below as first example, wherein, at Characteristics Control terminal and the control electricity of write transistor
Disposing capacity cell between extreme son, the control electrode terminal of write transistor is provided for controlling writes crystal
The control signal of the conduction/non-conduction of pipe.
When the transistor with the Characteristics Control terminal that can control threshold voltage is used as write transistor,
Can use constructed as below as second example, wherein, at Characteristics Control terminal with for transmission video signal
Video signal cable between dispose capacity cell.
First example or second example preferably include time constant adjustment member, are used for passing through capacity cell
Adjust the time constant of the signal being applied to Characteristics Control terminal.Time constant adjustment member can have connection
Resistive element to Characteristics Control terminal.That is, can be for providing signals to characteristic by capacity cell
On circuit (wiring) path of control terminal, resistive element is set.Line resistance when Characteristics Control terminal
When there is less resistance value and by the coupling of capacity cell, there is less effect, when being suitable for application
Between constant adjustment member.Specifically, when the time constant limited by capacity cell and Characteristics Control terminal
Line resistance less, and when the application time of coupled voltages is shorter, in the start time of signal write
The effect of the write capability increasing write transistor may be not enough.In such a case, for writing at signal
Start time increase write transistor write capability period can by time constant adjustment member increase time
Between constant extend.But, in this case, at time constant adjustment member and Characteristics Control terminal
Line resistance between formed bleeder circuit.Accordingly, it is considered to the Characteristics Control being applied to write transistor
The decline of the level of the characteristic control signal of terminal, is preferably provided with being formed the parts of time constant adjustment member
The constant (constant) of (such as resistive element).
When the transistor with the Characteristics Control terminal that can control threshold voltage is used as write transistor, can
Use constructed as below as third example, wherein, corresponding to the conduction/non-conduction for controlling write transistor
The pulse signal of control signal be applied to Characteristics Control terminal.Although third example and first case subclass
Seemingly, but the difference of third example and the first particle is characterized in particular in corresponding to for controlling write transistor
The pulse signal of the control signal of conduction/non-conduction is applied to the characteristic of write transistor by buffer
Control terminal.
In the 3rd situation, this structure preferably includes pulse width adjustment member and is applied to spy for adjusting
At least one in the amplitude adjustment member of the amplitude of the signal of property control terminal, this pulse width adjustment portion
Demultiplexing controls the pulse width of the control signal of the conduction/non-conduction of write transistor and is executed by signal in adjustment
Being added to Characteristics Control terminal, write transistor is arranged in conducting state (p17) by this pulse width.Obtain
With first example and second example similar purpose, it preferably has time constant adjustment member.Differential electricity
(differentiating circuit) can be used as pulse width adjustment member, and resistor voltage divider circuit on road
(resistance dividing circuit) can be used as amplitude adjustment member.Resistor voltage divider circuit can use as follows
Structure a: terminal of a resistive element is connected to the Characteristics Control terminal of write transistor, and this spy
The line resistance of property control terminal is used as another resistive element.
Device structure can include an image element circuit (display part), or can include pixel portion, at this
Pixel portion arranges display part with the form of line or two-dimensional matrix.Including the structure of pixel portion
In, Characteristics Control part preferably controls the characteristic of the write transistor in each display part.Including pixel
Part, with two-dimensional matrix form arrange display part structure in, Characteristics Control part can by scanning
The characteristic of the write transistor in each display element of processing controls.By way of parenthesis, when in each display element
When performing to control, the trap (well) of write transistor separates preferably independently of one another.As by-line (on a
Line-sequential basis) when performing light emitting control, often go separation trap gesture (well in (or each column)
Potential) (transistor characteristic control signal) is sufficient for, and is at least often going in (or each column)
The trap separating write transistor is sufficient for, but is not excluded for separating the trap of the write transistor in each display element.
Including emissive type luminous component, (such as organic electroluminescence emission part divides, inorganic EL is sent out
Light part, LED luminous component and semiconductor laser light emitting part) light-emitting component (display element)
Can be used as display part.Display part dtex does not preferably include organic electroluminescent luminous component.
<summary of display device>
In the following description, the resistance value of circuit structure parts, capacitance (electric capacity) etc. are available is attached to
The same reference numerals mark of parts, in order to simplify corresponding understanding.
[basic]
First the summary of the display device including light-emitting component is introduced.
In the following description of circuit structure, " electrical connection " will be briefly described as " connection ".Should " electricity
Connect " not only include being directly connected to, also include that (its typical example is switch by other transistor
Transistor) or other electric device (it is not limited to active component and can be also passive element) connect.
Display device includes multiple image element circuit (it also may be simply referred to as pixel).Each image element circuit has bag
Include the display element (electrooptic cell) of luminous component and be used for the drive circuit of driven for emitting lights part.Such as,
Including emissive type luminous component, (such as organic electroluminescence emission part divides, inorganic EL illuminating part
Point, LED luminous component and semiconductor laser light emitting part) light-emitting component can be used as display part.
By way of parenthesis, the driving system of constant current is used as driving the system of the luminous component of display element.But,
To be not limited to constant current driving for this system in principle, can be also that constant voltage is driving.
In following example to be introduced, organic electroluminescence emission part divides and is included as light-emitting component.More
Concrete, light-emitting component is organic electroluminescent device (organic EL element), and it has by stacking
(laminate) drive circuit and the organic electroluminescence emission part being connected to drive circuit divide (luminous component
ELP) structure formed.
The drive circuit of driven for emitting lights part ELP includes multiple circuit.And, image element circuit can include
The drive circuits such as 5Tr/1C type, 4Tr/1C type, 3Tr/1C type, 2Tr/1C type.In " α Tr/1C type "
Middle α represents the number of transistor." 1C " represents that capacitive part includes a storage capacitor CCS(electric capacity
Device).The transistor of each formation drive circuit is preferably n-channel transistor, but is not limited to this.?
In certain situation, a part of transistor can be p-channel-type.Subsidiary, transistor may be formed at quasiconductor
In substrate etc..Formed drive circuit transistor structure without particular limitation of, can use by MOS type FET
The isolated-gate field effect transistor (IGFET) that (general thin film transistor (TFT) (TFT)) represents.Drive it addition, formed
The transistor of circuit can be any one in enhancement mode or depletion type, or can be single grid-type or double grid
Any one in type.
In any configuration, display device substantially includes luminous component ELP, drives transistor TRD, write
Transistor TRW(also referred to as sampling (sampling) transistor), at least include writing the vertical of sweep test
Sweep test, the horizontal driving section with the function of segment signal output and storage capacitor CCS, as
As minimum element in the case of 2Tr/1C type.Preferably, in order to form bootstrapping (bootstrap)
Circuit, storage capacitor CCS is connected to drive transistor TRDControl input terminal (gate terminal)
With driving transistor TRDOne of main electrode terminal (source/drain region) (being typically source terminal) between.
Drive transistor TRDA main electrode terminal be connected to luminous component ELP, and drive transistor
TRDAnother main electrode terminal be connected to power supply (power supply) line PWL.From power circuit, use
Scanning circuits in supply voltage etc. apply supply voltage (steady state voltage or impulse form voltage) to electricity
Source line PWL.
Horizontal driving section provides has the video signal VS of broad sense to video signal cable DTL, this video
Signal represents the video signal V for controlling the brightness in luminous component ELPsigAnd for threshold correction
Reference potential (it is not necessarily one) etc..Write transistor TRWA main electrode terminal be connected to
Video signal cable DTL, and write transistor TRWAnother main electrode terminal be connected to drive transistor
TRDControl input terminal.Write sweep test and will be used for transistor TR by writing scan line WSLW's
The control pulse that ON/OFF (on/off) controls is applied to write transistor TRWControl input terminal.Write crystalline substance
Body pipe TRWMain electrode terminal another terminal, drive transistor TRDControl input terminal and deposit
Storage capacitor CCSA terminal between junction point will be referred to as primary nodal point ND1.Drive transistor
Device TRDA main electrode terminal and storage capacitor CCSAnother terminal between junction point will be claimed
It is the second node ND2。
The structure of example
Fig. 1 and Fig. 2 illustrates the active array type display dress of the embodiment such as the display device according to the disclosure
The block diagram of the summary of the example of the structure put.Fig. 1 is the structure illustrating common active matrix type display
The block diagram of the summary made.In the case of Fig. 2 is for providing coloured image to show, the frame of the summary of display device
Figure.
As it is shown in figure 1, display device 1 includes: display surface plate 100, in display surface plate 100,
Arrange have organic EL element (not shown) as multiple display elements image element circuit 10(also referred to as
Pixel), in order to formed and there is X:Y(such as 9:16) display aspect ratio (aspect ratio) effective
Video area;Signal generator is driven to divide 200(so-called timing generator), it is used for driving as generation
The example that the panel control section of the various pulse signals controlling display surface plate 100 divides;And video signal
Process part 220.In the present example, signal generator is driven to divide 200 and video signal processing section 220
It is contained in a chip IC (integrated circuit), and drives signal generator to divide 200 and video signal
Process part 220 and be positioned in the outside of display surface plate 100.
Subsidiary, as product form, display device 1 is not limited to be provided as module (ingredient)
Display device 1 in form, this modular form includes all of display surface plate 100, drives signal to produce
Part 200 and video signal processing section 220, as shown in FIG., but such as display surface plate
100 can be provided separately as display device 1.It addition, display device 1 also includes sealing (sealed)
The display device of modularity (modular) form of structure.Such as by by the back side of clear glass etc.
(counter) display module being partly laminated to pixel array portion 102 and formed is corresponding to this display
Device.Transparent backsides part can be set chromatic filter, protecting film, photomask etc..In order to from outside
Input or output video signal Vsig and various driving pulse are to pixel array portion 102, display module
Circuit part and FPC(flexible print circuit can be provided with) etc..
This display device 1 can be used as the display part in various electronic installation, i.e. electricity in all spectra
Sub-device, it is by the video signal exporting electronic installation or the video signal produced in an electronic
It is shown as rest image or mobile image (video), such as, uses and include semiconductor memory, small-sized
The record portable music player of medium, digital camera, the notes such as disk (MD), cassette tape
This PC, the mobile communication terminal including portable phone etc. and video camera.
Display surface plate 100 is included therein with the matrix arrangement image element circuit 10 of M row × N row
Pixel array portion 102, in the vertical driving section 103 of vertical scan direction image element circuit 10,
Horizontal driving section 106(for scanning element circuit 10 in the horizontal direction be also known as horizontal selector or
Person's data-line drive part), in each drive part (vertical driving section 103 and horizontal drive portion
Points 106) and the interface section 130 etc. of interface of external circuit, pixel array portion 102, vertically drive
Dynamic part 103, horizontal driving section 106, interface section 130, terminal part 108 etc. are integrated and shape
Become in substrate 101.That is, peripheral drive circuit (such as vertical driving section 103, horizontal drive portion
Points 106, interface section 130 etc.) it is formed in same substrate 101 as pixel array portion 102.
In Fig. 1 by 10_N, M mark be positioned at m row (m=1,2,3 ..., M) and n-th arrange (n=1,
2,3 ..., N) light-emitting component (image element circuit 10).
Interface section 130 has the vertical IF portion of the interface at vertical driving section 103 and external circuit
Points 133 and the horizontal IF part 136 of interface at horizontal driving section 106 and external circuit.
Vertical driving section 103 and horizontal driving section 106 are formed and control part 109, control part 109
For control signal electromotive force to the storage write of capacitor, threshold correction operation, mobility (mobility)
Correct operation and bootstrapping operation.Formed for driving the image element circuit controlled in pixel array portion 102
The driving control circuit of 10, this driving control circuit includes controlling part 109 and interface section 130(hangs down
Straight IF part 133 and horizontal IF part 136).
In the case of 2Tr/1C type, vertical driving section 103 includes that writing sweep test (writes scanning device
WS;Write scanning) and be used as have supply of electric power ability voltage sweep device driving sweep test (drive
Scanning device DS;Drive scanning).As an example, by vertical driving section 103 from the level side of Fig. 1
Side upwards or both sides drive pixel array portion 102, and by horizontal driving section 106 from
Side or both sides in the vertical direction of Fig. 1 drive pixel array portion 102.
Terminal part 108 is applied to the driving signal generator on the outside being arranged on display device 1
Divide the various pulse signals of 200.Terminal part 108 is applied from video signal processing section similarly
The video signal Vsig of 220.When provide colour display time, terminal part 108 be applied in different colours (
In this example, R(is red), G(green) and B(blue) three primary colours) and video signal Vsig_R, video letter
Number Vsig_GAnd video signal Vsig_B。
As an example, necessary pulse signal is applied as the pulse signal for vertical drive, this pulse
The displacement of the example that signal such as starts pulse as scanning in vertical direction starts pulse (shift
Start pulse) SP(two kinds, i.e. SPDS and SPWS in Fig. 1) and vertical scanning clock CK
(two kinds, i.e. CKDS and CKWS in Fig. 1), the vertical scanning clock of phasing back as required
XCK(two kinds, i.e. xCKDS and xCKWS in Fig. 1) and in particular moment marker pulse
The enabling pulse of output.Apply necessary pulse signal as horizontal drive pulse signal, this pulse signal
The level of the example such as starting pulse as scanning in the horizontal direction starts pulse and horizontal sweep
The horizontal sweep clock xCKH of clock CKH, as required phasing back and in particular moment
The enabling pulse of marker pulse output.
Each terminal of terminal part 108 passes through connection to vertical driving section 103 and horizontal drive
Part 106.Such as, each pulse of terminal part 108 it is applied to as desired by not shown in figure
Level displacement shifter partial interior adjust voltage level, and then each pulse is applied by buffer
To vertical driving section 103 and each part of horizontal driving section 106.
Not shown although (will be described in detail below), in pixel array portion 102, in the matrix form
The pixel with pixel transistor provided as the organic EL element of display element is provided two-dimensionally
Circuit 10.For pixel arrange each row arrange vertical scan line SCL, and for pixel layout each
Row arrange video signal cable DTL.That is, image element circuit 10 is connected to vertically by vertical scan line SCL
Drive part 103, and image element circuit 10 is connected to horizontal driving section by video signal cable DTL
106.Especially, for each pixel column of the image element circuit 10 of matrix arrangement, arrange for by
Vertical scan line SCL_1 to the SCL_M of the m row that vertical driving section 103 is driven by driving pulse.
Vertical driving section 103 is formed by the combination of gate (including latch, shift register etc.).Base
Next self-driven signal generator in vertical drive system divides the pulse signal of 200, vertical driving section 103
The image element circuit 10 of the pixel array portion 102 in alternative column unit, i.e. by vertical scan line SCL even
Continuous selection image element circuit 10.Horizontal driving section 106 (is included latch, shift register by gate
Deng) combination formed.Next self-driven signal generator based on horizontal driving system divides the pulse of 200 to believe
Number, the image element circuit 10 of the pixel array portion 102 in horizontal driving section 106 alternative column unit, i.e.
Make the selected image element circuit 10 predetermined potential by video signal cable DTL sample video signal VS
(such as adaptation signal VsigLevel) and by electromotive force write storage capacitor CCS。
Display device 1 according to the present embodiment can by-line (line-sequential) drive or pointwise
(dot-sequential) drive.The writing sweep test 104 and drive sweep test of vertical driving section 103
105 by-lines (that is, with behavior unit) scanning element array portion 102, and Tong Bu with this, and level is driven
Dynamic part 106 is by (in the case of by-line drives) while of a horizontal picture signal or with pixel
For in unit (in the case of pointwise drives) writing pixel array portion 102.
As in figure 2 it is shown, such as in order to coloured image shows, pixel array portion 102 has predetermined
The image element circuit 10 of the vertical bar form of arrangement orderR, image element circuit 10GWith image element circuit 10BAs not
Same color (in the present example, R(is red), G(are green) and B(blue) three primary colours) and sub-pixel.
One sub-collection of pixels of different colours forms a colour element.Although illustrating in this case to hang down
Vertical bar form arranges the bar structure example as subpixel layouts of the sub-pixel of each color, sub-pixel cloth
Office is not limited to the example of this layout.Also can use the form of displacement sub-pixel in vertical direction.
Subsidiary, although Fig. 1 and Fig. 2 illustrates have the side being arranged only at pixel array portion 102
Vertical driving section 103(is specially the element of vertical driving section 103) structure, but can be
The element of vertical driving section 103 is all arranged on the left side of insertion pixel array portion 102 therebetween and right side.
It addition, the one of vertical driving section 103 may be arranged on corresponding left side and right side with other elements.
It is similar to, although Fig. 1 and Fig. 2 illustrates the water having on the side being arranged only at pixel array portion 102
The structure of flat drive part 106, but can be in the upper side and lower side of the pixel array portion 102 inserted therebetween
All arrange horizontal driving section 106.Although in the present example from the outside input arteries and veins of display surface plate 100
(such as vertical displacement starts pulse, vertical scanning clock, level starts pulse and level is swept to rush signal
Retouch clock), but the driving signal generator for producing these various commutator pulses divide 200 may be provided at aobvious
Show in panel block 100.
Structure shown in figure is merely representative of a kind of form of display device.Can take other form as product
Product form.In other words, whole display device is formed to include being sufficient for lower part, i.e. includes having
Form the pixel array portion of the element of the image element circuit 10 arranged in the matrix form, be arranged in pel array
The control part (as major part) of portion, is connected to drive the scanning of the scan line of each pixel
Partly and for producing the driving signal generator of the various signals of operation control part divide and video letter
Number process part.As product form, (this form is referred to as plate not only can to use the form shown in figure
Upper layout constructs), in form shown in the figure, have and be arranged on same substrate (such as substrate of glass)
On pixel array portion and control part display surface plate with drive signal generator divide and video signal
Process part separately, and (this form is referred to as the layout structure of peripheral circuit outside plate also can to use following form
Make): pixel array portion is arranged in display surface plate, and peripheral circuit (such as control part, drives
Dynamic signal generator divides and video signal processing section) it is arranged on the substrate (example separated with display surface plate
Such as flexible board) on.It addition, by pixel array portion and control part are arranged on the same base
And formed and arrange in the case of structure on the plate of display surface plate, (this form will claim can to use following form
For the integrated structure of transistor): in the process that pixel array portion is formed TFT, concurrently form control portion
Divide each transistor of (driving signal generator to divide and video signal processing section as required), and
Following form (this form is referred to as COG and arranges structure) can be used: be used for controlling part (and such as institute
The driving signal generator needed divides and video signal processing section) semiconductor chip by COG(glass
Upper chip) technology of setting is set directly on it and is provided with in the substrate of pixel array portion.Alternatively,
Can only provide display surface plate (at least including pixel array portion) as display device.
<light-emitting component>
Fig. 3 A and 3B is to aid in explaining that the light-emitting component 11(equivalence including drive circuit is image element circuit
10) figure.Fig. 3 A is light-emitting component 11(image element circuit 10) the imperfect cross section of signal of part regard
Figure.Fig. 3 B is the cross sectional view of the example of mos transistor structure.Assume the insulated gate field in Fig. 3 A
Effect transistor is thin film transistor (TFT) (TFT).But, as below by will described in example described in,
In the present embodiment, the MOS transistor phase shown in so-called back of the body gate type thin film transistor or Fig. 3 B
Hope and be at least used as write transistor TRW.MOS type shown in Fig. 3 B is particularly suited for use as write transistor
TRW.This is because the thin film transistor (TFT) of back of the body grating structure relates to complex fabrication process (or being difficult to manufacture),
But in the MOS type shown in figure 3b, first semiconductor base or trap play backgate (also referred to as
Block (bulk)) effect.
As shown in Figure 3A, each transistor and the capacitance part of the drive circuit of light-emitting component 11 are such as formed
Divide (storage capacitor CCS) be formed on supporter (support) 20, and luminous component ELP shape
Become and forming each transistor and the storage capacitor C of drive circuitCSTop, wherein interlayer insulative layer 40
It is inserted in luminous component ELP and each transistor and storage capacitor CCSBetween.Drive transistor
TRDOne of source/polar region be connected to arrange the anode electrode of luminous component ELP by contact hole.Figure
3A and 3B only illustrates driving transistor TRD.View conceals write transistor TRWCrystal with other
Pipe.Luminous component ELP has known structure and structure, including such as anode electrode, hole transport layer,
Luminescent layer, electron transfer layer and cathode electrode.
Concrete, drive transistor TRDIncluding gate electrode 31, gate insulation layer 32, semiconductor layer 33,
The source/drain region 35 being arranged in semiconductor layer 33 and channel formation region 34, between source/drain region 35
Semiconductor layer 33 correspond partly to this region 34.Storage capacitor CCSBy another electrode 36, by grid
Dielectric layer and an electrode 37(that the extension of insulating barrier 32 is formed correspond to secondary nodal point ND2)
Constitute.Gate electrode 31, the part of gate insulation layer 32 and formation storage capacitor CCSAnother electrode
36 are formed on supporter 20.Drive transistor TRDA source/drain region 35 be connected to circuit 38.
Another source/drain region 35 is connected to this electrode 37.Drive transistor TRD, storage capacitor CCSDeng
Covered by interlayer insulative layer 40.By anode electrode 51, hole transport layer, luminescent layer, electron transfer layer with
And the luminous component ELP that cathode electrode 53 is constituted is arranged on interlayer insulative layer 40.In figure 3 a,
Hole transport layer, luminescent layer and electron transfer layer is represented by a layer 52.Second interlayer insulative layer 54
It is arranged in the part of interlayer insulative layer 40, is not provided with luminous component ELP on the portion.Transparent substrates
21 are arranged on the second interlayer insulative layer 54 and cathode electrode 53.Transmitted in luminescent layer by substrate 21
The light produced, and outside will be output this light to.This electrode 37 and anode electrode 51 are by setting
The contact hole put in interlayer insulative layer 40 is connected to each other.Cathode electrode 53 is by contact hole 56 and connects
Contact hole 55 is connected to the circuit 39 being arranged on the extension of gate insulation layer 32, and this contact hole 55 sets
Put in the second interlayer insulative layer 54 and interlayer insulative layer 40.
In structure shown in figure 3 a, when TFT is MOS transistor, as shown in Figure 3 B, grid
(narrow region raceway groove) is formed at partly leading of the first polarity (p-type or N-type (for N-type in Fig. 3 B))
On the surface of body substrate, and it is attached gate terminal so that with the oxidation being inserted between gate terminal and raceway groove
Film (particularly referred to as gate oxidation films) covers raceway groove.Such as polysilicon can be used as the material of gate terminal, and
It is specifically referred to as polysilicon gate (poly-gate).It addition, form oxide-film (particularly referred to as field oxide film),
The entirety of gate terminal is included to cover, and the second polarity that hereafter attachment is different from the first polarity (
This situation is p-type) source region and each terminal (respectively source terminal and the drain terminal) conduct in drain region
The metal material at gate terminal two ends.Therefore, the MOS of the second polarity (being p-type in this case) is brilliant
Body pipe (PMOS) (P-type device) is formed at the surface layer of the semiconductor base of the first polarity (N-type)
In.Backgate in the P-type device of this structure is N-type substrate, and this backgate is not individually separated.
The signal that may not perform individually or often with going (or each column) separate P-type device applies, but can
To apply the control signal common to all P-type device of pixel array portion 102.In order in the first pole
Property (N-type) semiconductor base surface layer in form the first polarity (in situation for N-type)
MOS transistor (NMOS) (N-type device), at the table of the semiconductor base of the first polarity (N-type)
Face forms the trap of the second polarity (p-type), and then using this trap (p-well) as the second polarity (p-type)
Semiconductor base and be similarly constructed grid region, source region, drain region etc. and be sufficient for.The N-type device of this structure
The trap of the second polarity (p-type) in part can separate individually or often with going (or each column), and because of
This can separate trap electromotive force (transistor characteristic control signal Vb) individually or often with going (or each column).
Subsidiary, the surface layer of the semiconductor base of the first polarity (N-type) forms the second polarity (at this
Situation is p-type) MOS transistor (PMOS) (P-type device) in, the first polarity (N-type)
The trap semiconductor base that may be formed at the first polarity (N-type) surface in (seeing the dotted line in Fig. 3 B),
And hereafter this trap (N trap) can be regarded as the first polarity (N-type) semiconductor base and similarly
Form grid region, source region, drain region etc..Then, can individually or often with going (or each column) separately
The trap of the first polarity (N-type) in the P-type device of this structure, and therefore can individually or often go
(or each column) ground separately trap electromotive force (transistor characteristic control signal Vb).Pass through element isolation region
P-type device (PMOS) and N-type device (NMOS) are separated from each other.
<driving method: basis>
The method of driven for emitting lights part explained below.In order to make it easy to understand, assume by n-channel type brilliant
The tubular each transistor being shaped as image element circuit 10 of body is introduced.In addition, it is assumed that luminous component
The anode terminal of ELP is connected to the second economize on electricity ND2, and the cathode terminal of luminous component ELP is connected to
Cathode circuit cath(assumes that the electromotive force of cathode circuit cath is cathode potential Vcath).It addition, according to drain electrode
Electric current IdsThe size of value control the luminance (brightness) in luminous component ELP.At light-emitting component
In luminance, drive transistor TRD(an illuminating part of two main electrode terminals (source/drain region)
Divide the anode-side of ELP) it is used as source terminal (source region), and another is as drain terminal (drain region).False
If display device colored can show and include (N/3) × M the pixel electricity arranged with two-dimensional matrix form
Road 10, and assume that the image element circuit forming a color display unit includes three sub-pixel circuits
(launch the red light emitting pixel circuit 10 of HONGGUANGR, launch the green light emitting pixel circuit 10 of green glowG, launch indigo plant
The blue light emitting pixel circuit 10 of lightB).Assume that by-line drives the light-emitting component forming each image element circuit 10,
And assume that display frame frequency is FR(number/second).That is, m row (wherein m=1,2,3 ...,
M) arrange (N/3) individual image element circuit 10, more specifically, simultaneously drive and form N number of pixel electricity respectively
The light-emitting component on road 10.In other words, control to be formed the transmitting/no of the light-emitting component of a line with behavior unit
The timing launched, these light-emitting components belong to this line.Subsidiary, video signal is write formation a line
The process of image element circuit 10 can be video signal is simultaneously written to the process of all image element circuits 10 (should
Process also referred to as will write process simultaneously), or can be that video signal is sequentially write each image element circuit
The process (this process is referred to as sequential write and processes) of 10.According to the structure of drive circuit, properly select one
Individual write process and be sufficient for.
Driving operation about the light-emitting component being positioned at m row and the n-th row explained below.Subsidiary,
Be positioned at the light-emitting component of m row and the n-th row will be referred to as the (n, m) light-emitting component or the (n,
M) light-emitting component image element circuit.When for being arranged in the horizontal sweep of each light-emitting component of m row
Section is before (m horizontal sweep period) terminate, perform multiple process (threshold correction processes, write process,
Mobility (mobility) correction process etc.).Subsidiary, write process and mobility correction process needs
The m horizontal sweep period performs.On the other hand, according to the type of drive circuit, at threshold correction
Reason and the pretreatment processed with threshold correction can perform before the m horizontal sweep period.
After each process described above all completes so that it is each that formation is arranged in m row
The luminous component of light-emitting component is luminous.Subsidiary, can make luminous component after each process all completes
Luminous immediately, or make luminous component through scheduled time slot (example after all of multiple process complete
The horizontal sweep period such as predetermined number of lines) time luminous.Specification (specification) according to display device,
Image element circuit 10(i.e. drive circuit) structure etc. suitably set " scheduled time slot " and be sufficient for.Hereinafter,
Introduce for convenience, it is assumed that make luminous component luminous immediately after multiple process complete.Formed and arrange
The luminescence of the luminous component of each light-emitting component in m row proceeds to just for being arranged in
Before the horizontal sweep period of each light-emitting component in (m+m ') row starts.Setting according to display device
Meter specification determines that " m ' " is sufficient for.That is, formed in the m row that is arranged in particular display frame is each
The luminescence of the luminous component of light-emitting component proceeds to (m+m '-1) till the horizontal sweep period.The opposing party
Face, the m horizontal sweep started to next one display frame of (m+m ') horizontal sweep period from the
Process of writing in period completes with mobility correction process, forms each luminous unit being arranged in m row
The luminous component of part keeps non-emitting states in principle.(this period also will the period assuming non-emitting states
It is referred to as the non-emissive period) to reduce image retention adjoint in driven with active matrix fuzzy (afterimage blur),
And therefore obtain the most mobile picture quality.But, each image element circuit 10(light-emitting component)
Emission state/non-emitting states is not limited to state described above.The time span of horizontal sweep period is little
In (1/FR) × (1/M) second.When the value of (m+m ') is more than M, locate in next one display frame
The horizontal sweep period that reason exceedes.
(on) state (conducting state) of opening of transistor refers to the main electrode terminal (source/drain at transistor
District) between form the state of passage, and it is main not consider whether electric current flows to another from a main electrode terminal
Electrode terminal.Pass (off) state (nonconducting state) of transistor refers to the main electrode end at transistor
The state of passage is not formed between son.It is connected to the special transistor of the main electrode terminal of another transistor
The state of main electrode terminal includes following form: the source/drain region of this special transistor and another transistor
Source/drain region occupies identical region.It addition, source/drain region not only can be by such as comprising the polysilicon of impurity or non-
The conductive materials of crystal silicon etc. is formed, also can be by metal, alloy, conducting particles, its stepped construction or have
The layer that machine material (conductive polymer) is made is formed.In the sequential chart of middle use introduced below, instruction
The length (time span) of the axle of the abscissa of each period is schematic, does not indicates that each period
The ratio of time span.
The method driving image element circuit 10 includes that pre-treatment step, threshold correction process step, video signal
Write process step, mobility aligning step and step of transmitting.Pre-treatment step, threshold correction process step
Suddenly, video signal writes process step, mobility aligning step will be collectively known as non-emissive step.Foundation
The structure of image element circuit 10, video signal writes process step and mobility aligning step can perform simultaneously.Will
The summary of each step is described.
Subsidiary, according to below equation (1), the driving transistor in the luminance of driven for emitting lights element
TRD, in order to by drain current Ids.Drain current IdsFlow through luminous component ELP, thus luminous component
ELP launches light.It addition, according to drain current IdsThe size of value control the luminescence in luminous component ELP
State (brightness).In the luminance of light-emitting component, drive transistor TRDTwo main electrode terminals
One (the anode terminal side of luminous component ELP) in (source/drain region) is used as source terminal (source region),
Another is used as drain terminal (drain region).Introduce for convenience, in introduced below, drive transistor TRD
A main electrode terminal can be simply referred as source terminal, and another main electrode terminal can be simply referred as
Drain terminal.
Ids=k·μ·(Vgs–Vth)2(1)
Wherein k is coefficient k ≡ (1/2) (W/L) COX, L is channel length, and W is channel width,
And COXIt is equivalent capacitance value ((relative dielectric constant of gate insulation layer) × (dielectric constant of vacuum)
/ (thickness of gate insulation layer)), μ is effective mobility, VgsIt it is electromotive force (the grid electricity controlling electrode terminal
Gesture Vg) and electromotive force (the source electromotive force V of source terminalsElectric potential difference (gate source voltage) between), and Vth
It it is threshold voltage.
In described below, except as otherwise noted, it is assumed that the electric capacity of the parasitic capacitance of luminous component ELP
Value CelWith storage capacitor CCSCapacitance CCSWith as drive capacitor TRDThe example of parasitic capacitance
It is sufficiently large value that gate-source capacitance value Cgs of son compares, and does not consider based on driving transistor TRD
Gate terminal electromotive force (gate potential Vg) change and cause drive transistor TRDSource region (secondary nodal point
ND2) electromotive force (source voltage Vs) change.
[pre-treatment step]
Primary nodal point initialization voltage (Vofs) it is applied to primary nodal point ND1And the second economize on electricity initializes electricity
Pressure (Vini) it is applied to secondary nodal point ND2, thus primary nodal point ND1With secondary nodal point ND2Between
Electric potential difference exceedes driving transistor TRDThreshold voltage Vth, and it is supplied to the of luminous component ELP
Two node ND2With the electric potential difference between cathode electrode is less than the threshold voltage V of luminous component ELPthEL。
Assume such as to control the video signal V of the brightness in luminous component ELPsigIt is 0 to 10 volts, power supply electricity
Pressure is 20 volts, drives transistor TRDThreshold voltage VthIt is 3V, cathode potential VcathIt it is 0 volt
Spy, and the threshold voltage V of luminous component ELPthELIt it is 3 volts.In this case, it is assumed that initial
Change and drive transistor TRDElectromotive force (the gate potential V of control input terminalg, i.e. primary nodal point ND1Electricity
Gesture) electromotive force VofsIt is 0 volt, and assumes to initialize driving transistor TRDThe electromotive force of source terminal
(source electromotive force Vs, i.e. secondary nodal point ND2Electromotive force) electromotive force ViniIt it is-10 volts.
[threshold correction process step]
Keeping primary nodal point ND1Electromotive force state in, drain current IdsThrough driving transistor TRD,
And secondary nodal point ND2Electromotive force towards by from primary nodal point ND1Electromotive force in deduct driving transistor
TRDThreshold voltage VthAnd the electromotive force obtained and change.Now, after pre-treatment step, exceed logical
Cross and will drive transistor TRDThreshold voltage VthPlus secondary nodal point ND2Electromotive force and the voltage that obtains
Voltage (supply voltage of such as fluorescent lifetime) be applied to drive transistor TRDAnother main electrode
Terminal (on the opposition side of secondary nodal point).In threshold correction processes step, primary nodal point ND1With
Two node ND2Between electric potential difference (or drive transistor TRDGate source voltage Vgs) close to driving
Transistor TRDThreshold voltage VthDegree depend on the time that threshold correction processes.Thus, such as
When guaranteeing that threshold correction processes enough for a long time, secondary nodal point ND2Electromotive force reach by from first
Node ND1Electromotive force in deduct driving transistor TRDThreshold voltage VthAnd the electromotive force obtained, and
Drive transistor TRDIt is arranged in off status.On the other hand, such as when the time that threshold calibration processes
When needs are set to shorter, the first electromotive force ND1With the second electromotive force ND2Between electric potential difference can be more than driving
Dynamic transistor TRDThreshold voltage Vth, and drive transistor TRDOff status may be not arranged at
In.The result processed as threshold correction, drives transistor TRDIt is not necessary to be arranged in off status.
Subsidiary, in threshold correction processes step, preferably by selection and determine electromotive force to meet formula (2) and
Luminous component ELP is stoped to launch light.
(Vofs–Vth)<(VthEL+Vcath) (2)
[video signal writes process step]
By writing driving pulse WS, by video signal V from write scan line WSLsigFrom video signal
Line DTL is via the write transistor TR being arranged on open stateWIt is applied to primary nodal point ND1, and first
Node ND1Electromotive force rise to Vsig.Based on primary nodal point ND1The change (V of electromotive forcein=Vsig-Vofs)
Electric charge by substep to storage capacitor CCS, parasitic capacitance C of luminous component ELPelAnd driving crystal
Pipe TRDParasitic capacitance (such as gate-source capacitance Cgs).As capacitance Cel and capacitance CCSAnd electric capacity
Value Cgs(such as gate-source capacitance CgsDeng) compare the most sufficiently large value time, secondary nodal point ND2Electromotive force
(V is changed based on electromotive forcesig-Vofs) change less.Generally, parasitic capacitance C of luminous component ELPel
Capacitance CelMore than storage capacitor CCSCapacitance CCSWith gate-source capacitance CgsCapacitance Cgs。
Considering this, unless needed especially, not considering by primary nodal point ND1Electromotive force change and cause second
Node ND2Electromotive force change.In this case, gate source voltage VgsFormula (3) can be passed through represent.
Vg=Vsig
Vs≈Vofs-Vh
Vgs≈Vsig–(Vofs–Vth) (3)
[mobility correction process step]
When by write transistor TRWBy video signal VsigIt is applied to store capacitor CCSA terminal
(i.e. when corresponding to video signal VsigDriving voltage be written to store capacitor CCS) time, electric current passes through
Drive transistor TRDAnd storage capacitor C is provided toCS.Such as, by from writing scan line WSL
Write driving pulse WS by video signal VsigFrom video signal cable DTL via being arranged on open state
Write transistor TRWIt is applied to primary nodal point ND1State in, to drive transistor TRDElectric power is provided,
To feed drain current Ids, thus change secondary nodal point ND2Electromotive force.After scheduled time slot,
Write transistor TRDIt is arranged in off status.Assume that the electromotive force of now secondary nodal point ND2 changes into Δ V
(=potential correction value or degenerative amount).The scheduled time slot performing mobility correction process is defined as
The value that is pre-designed during display device design is sufficient for.Subsidiary, now, preferably determine that mobility corrects
Period meets formula (2A).This stops luminous component ELP to launch light during the mobility correction period.
(Vofs–Vth+ΔV)<(VthEL+Vcath) (2A)
When driving transistor TRDMobility [mu] when being higher value, increase potential correction value Δ V.When driving
Dynamic transistor TRDMobility [mu] when being smaller value, reduce potential correction value Δ V.Drive transistor TRD
Gate source voltage Vgs(primary nodal point ND1With secondary nodal point ND2Between electric potential difference) now can with public affairs
Formula (4) represents.Gate source voltage VgsDetermine brightness during luminescence.Potential correction value Δ V and driving crystal
Pipe TRDDrain current IdsProportional, and drain current IdsProportional to mobility [mu].As a result,
Mobility [mu] is the highest, and value Δ V is the biggest for potential correction.Therefore, it can eliminate in each pixel current 10
The change of mobility [mu].
Vgs≈Vsig-(Vofs-Vth)-Δ V (4)
Subsidiary, when changing an expression, when video signal is passed through write transistor TRWIt is applied to drive crystalline substance
Body pipe TRDControl input terminal and storage capacitor a terminal time, mobility correction process can
It is referred to as by driving transistor TRDElectric current is provided the process of storage capacitor.
[step of transmitting]
By writing driving pulse WS by write transistor TR from write scan line WSLWIt is arranged on pass shape
By primary nodal point ND in state1It is arranged on suspension (floating) state, and applies power to drive
Transistor TRD, thus by driving transistor TRDWould correspond to drive transistor TRDGate source voltage
Vgs(primary nodal point ND1With secondary nodal point ND2Between electric potential difference) electric current IdsIt is fed into illuminating part
Divide ELP.Thus driven for emitting lights part ELP launches light.
[according to the difference of the structure of drive circuit]
Difference between typical types, following 5Tr/1C type, 4Tr/1C type, 3Tr/1C type and
2Tr/1C type.5Tr/1C type includes the first transistor TR1(light emitting control transistor), for applying second
The transistor seconds TR of node initializing voltage2And for applying the 3rd of primary nodal point initialization voltage
Transistor TR3, this first transistor TR1It is connected to drive transistor TRDMains side on main electrode
Between terminal and power circuit (power pack).The first transistor TR1, transistor seconds TR2With
Three transistor TR3It it is each switching transistor.The first transistor TR1Emission period is arranged on out
In state, it is arranged in off status to start the non-emissive period, in the follow-up threshold correction period again
It is arranged in open state, and after the mobility correction period neutralizes (also in next emission period)
It is additionally arranged in open state.Transistor seconds TR2Only in secondary nodal point initialization period, it is arranged on out shape
In state, otherwise it is arranged in off status.Third transistor TR3Only from primary nodal point initialization period to
It is arranged in open state during the threshold correction period, is otherwise arranged in off status.Write transistor TRW?
From video signal write process the period be arranged on open state during the mobility correction process period, otherwise set
Put in off status.
In 4Tr/1C type, omit from 5Tr/1C type for apply primary nodal point initialization voltage the
Three transistor TR3.About video signal Vsig, sequentially apply primary nodal point from video signal cable DTL
Initialization voltage.In order to primary nodal point initialization voltage being believed from video in primary nodal point initialization period
Number line DTL is applied to primary nodal point, also by write transistor TR in primary nodal point initialization periodWIf
Put in open state.Typically, write transistor TRWFrom primary nodal point initialization period to mobility school
Just processing the period of period is arranged in open state, is otherwise arranged in off status.
In 3Tr/1C type, from 5Tr/1C type, omit transistor seconds TR2With third transistor TR3。
About video signal Vsig, based on the time-division, apply primary nodal point from video signal cable DTL initialize electricity
Pressure and secondary nodal point initialization voltage.In order to secondary nodal point being arranged in secondary nodal point initialization period
Secondary nodal point initialization voltage, and in follow-up primary nodal point initialization period, primary nodal point is arranged
To primary nodal point initialization voltage, corresponding to the voltage V of secondary nodal point initialization voltageofs_HIt is applied as
The electromotive force of video signal cable DTL, and the electromotive force of video signal cable DTL is then set to first segment
Point initialization voltage Vofs_L(=Vofs).Corresponding to this, at primary nodal point initialization period and second section
In some initialization period, write transistor TRWIt is also disposed in open state.Typically, from secondary nodal point
Initialization period to period of mobility correction process period by write transistor TRWIt is arranged in open state,
Otherwise it is disposed in off status.
Subsidiary, in 3Tr/1C type, by using video signal cable DTL to change secondary nodal point ND2
Electromotive force.For this purpose, will storage capacitor C when designCSCapacitance CCSIt is set to
(such as capacitance C bigger than the capacitance in other drive circuitCSIt is capacitance CelAbout 1/4 to 1/3).
Accordingly, it is considered to, compared with other drive circuit, by primary nodal point ND1Electromotive force change the caused
Two node ND2Electromotive force change degree bigger.
In 2Tr/1C type, from 5Tr/1C type, omit the first transistor TR1, transistor seconds TR2
With third transistor TR3.About video signal Vsig, execute from video signal cable DTL based on timesharing
Add primary nodal point initialization voltage.By with the first electromotive force VCC_H(in 5Tr/1C type=VCC) and the
Two electromotive force VCC_L(in 5Tr/1C type=Vini) pulsed drive driving transistor TRDMains side on
Main electrode terminal, it is provided that secondary nodal point initialization voltage.Drive transistor TRDMains side on main electricity
Extreme son is set to the first electromotive force V in emission periodCC_H, and it is set to the second electromotive force VCC_L
To start the non-emissive period.Drive transistor TRDMains side on main electrode terminal in threshold value subsequently
In and after the correction period, (also in next emission period) is set to the first electromotive force VCC_H.In order to
Primary nodal point initialization voltage from video signal cable DTL is applied to by primary nodal point initialization period
Primary nodal point, write transistor TRWPrimary nodal point initialization period is also disposed in open state.Typical case
, write transistor TRWSetting to the period of mobility correction process period from primary nodal point initialization period
Put in open state, be otherwise arranged in off status.
Subsidiary, although it is described above situations below: threshold voltage and mobility are carried out school
Just process, as the change of the characteristic driving transistor but it also may only in threshold voltage and mobility
One execution correction process.
Although being made that described above based on preferable example, but this technology is not limited to these examples.Formed
The structure of each element of display device, display element and drive circuit described in each example
It is exemplary for making with the step in the method for structure and driven for emitting lights part, and can do and suitably change
Become.
It addition, write process and mobility in the operation of 5Tr/1C type, 4Tr/1C type and 3Tr/1C type
Correction can perform separated from one anotherly, or mobility correction process and write process and can perform simultaneously, as
In 2Tr/1C type.Concrete, by by the first transistor TR1(light emitting control transistor) is arranged on out
Via write transistor TR in stateWBy video signal VsigIt is applied to primary nodal point just foot from data wire DTL
It is enough,.
The object lesson of application
Explained below control drives transistor TRDThreshold voltage VthThe concrete example of application of technology
Son.Subsidiary, in the display device using active matrix organic EL panel, such as, it is arranged on
Panel both sides are all or the vertical overscan portion of side produces the control input terminal of transistor to be supplied to
Various gate signals (control pulse), and apply this signal to image element circuit 10.It addition, use this
The display device of organic EL panel can use 2Tr/1C type image element circuit 10 to reduce element number and
Obtain higher definition.In view of this, below by the representative example to the application that 2Tr/1C type constructs
Son illustrates.
[first embodiment]
[image element circuit]
Fig. 4 and Fig. 5 be illustrate according to for each embodiment the first comparative example image element circuit 10X with
And include the figure of the composition of the display device of image element circuit 10X.In pixel array portion 102, there is root
The display dress according to the first comparative example will be referred to as according to the display device of the image element circuit 10X of the first comparative example
Put 1X.Fig. 4 illustrates the essential structure of (pixel).Fig. 5 illustrates that (whole display fills specific configuration
Put).Fig. 6 and Fig. 7 is to illustrate the image element circuit 10Y according to the second comparative example for each embodiment
And include the figure of the display device of image element circuit 10Y.Pixel array portion 102 has according to
The display device of the image element circuit 10Y of two comparative examples will be referred to as the display device according to the second comparative example
1Y.Fig. 6 illustrates the essential structure of (pixel).Fig. 7 illustrates specific configuration (whole display device).
Fig. 8 and Fig. 9 is to illustrate the image element circuit 10A according to first embodiment and include this image element circuit 10A
The figure of composition of display device.There is in pixel array portion 102 pixel according to first embodiment
The display device of circuit 10A will be referred to as display device 1A according to first embodiment.Fig. 8 illustrates (one
Individual pixel) essential structure.Fig. 9 illustrates specific configuration (whole display device).Subsidiary, each
In comparative example and first embodiment, it is arranged on the vertical driving section of the periphery of image element circuit 10
103 and horizontal driving section 106 be also shown in the substrate 101 of display surface plate 100.To later
Other embodiments to be described also is same.
To first describe comparative example and the common part of first embodiment, wherein omit reference A, attached
Figure labelling X and reference Y.Display device 1 is based on video signal Vsig(specially signal amplitude Vin)
(organic EL element 127 is used as luminous component in the present example to make the electrooptic cell in image element circuit 10
ELP) light is sent.For this purpose, display device 1 in pixel array portion 102 with rectangular
Include in each image element circuit 10 that formula is arranged producing at least one the driving transistor 121 driving electric current
(drive transistor TRD), be connected to drive transistor 121 control input terminal (control input terminal
Exemplary be gate terminal) and drive transistor 121 the lead-out terminal (exemplary of lead-out terminal
Source terminal) between storage capacitor 120(store capacitor CCS), as be connected to drive crystal
The organic EL element 127(light output part of the example of the electrooptic cell of the lead-out terminal of pipe 121 divides ELP),
And be used for would correspond to signal amplitude VinInformation write storage capacitor 120 sampling transistor
125.In image element circuit 10, produce in driving transistor 121 and keep based on storage capacitor 120
The driving electric current I of informationds, and drive electric current IdsOrganic EL through the example as electrooptic cell
Element 127, so that organic EL element 127 sends light.
Sampling transistor 125 would correspond to signal amplitude VinInformation write storage capacitor 120.Therefore,
Sampling transistor 125 is at the input terminal (in source terminal and drain terminal) of sampling transistor 125
Accept signal potential (Vofs+Vin), and would correspond to signal amplitude VinInformation write be connected to sampling
The storage capacitor 120 of the lead-out terminal of transistor 125 (in source terminal and drain terminal another).
Certainly, the lead-out terminal of sampling transistor 125 is also connected to drive the control input terminal of transistor 121.
Subsidiary, the connecting structure of image element circuit 10 illustrated above represents most basic structure.Pixel electricity
Road 10 at least includes that element described above is sufficient for, and image element circuit 10 includes except these
Other element (i.e. other element) outside element.It addition, " connection " is not limited to directly connect
Connect, can be also to be connected by other element.For example, it is also possible on demand connection spacing is changed
Become, such as, insert switching transistor, there is the functional part etc. of specific function.Typically, dynamically control
The switching transistor of display time interval (launch time) can be arranged on the outfan driving transistor 121
Between son and electrooptic cell (organic EL element 127), or it is arranged on the electric power driving transistor 121
Supply terminal (exemplary of supply of electric power terminal is drain terminal) and the electric lines of force as power circuit
PWL(is power line 105DSL in the present example) between.If the pixel in this modification
Circuit makes it possible to realize structure to be described and action in first embodiment (or other embodiments),
These modification are also the image element circuits 10 of the embodiment realizing the display device according to the disclosure.
It addition, drive the periphery of image element circuit 10 such as to have control part 109, this control part
109 include: write sweep test 104, for being held by sequential control sampling transistor in horizontal period
The by-line scanning of row image element circuit 10, would correspond to video signal VsigSignal amplitude VinInformation
Write in each storage capacitor 120 of a line;And drive sweep test 105, export turntable driving
Pulse (driven by power pulse DSL), for coordinating mutually to scan with the by-line writing sweep test 104
(coordinate) mode controls to be applied to the electricity of the power supply terminal of each driving transistor 121 of a line
Source.Control part 109 and also include horizontal driving section 106, be used for performing control so that at each water
At ordinary times will be at reference potential (V in sectionofs) and signal potential (Vofs+VinThe video signal of change between)
VsigIt is applied to sampling transistor 125 in the way of coordinating mutually with the progressive scan writing sweep test 104.
Control part 109 preferably to be carried out controlling, with by would correspond to signal amplitude VinInformation write
Sampling transistor 125 is set to nonconducting state by the time point of storage capacitor 120, stops video
Signal VsigIt is applied to drive the control input terminal of transistor 121, and performs bootstrapping operation, at this
Bootstrapping operation drives the electromotive force of the control input terminal of transistor 121 and the output driving transistor 121
Change operation ground association in the electromotive force of terminal.Control part 109 the most also after sampling operation terminates
The luminous starting stage started perform bootstrapping operation.That is, part 109 is controlled at signal potential (Vofs+Vin)
It is applied in the state of sampling transistor 125 be arranged in conducting state sampling transistor 125, and
And hereafter sampling transistor 125 is arranged in nonconducting state so that drive the control of transistor 121
Electric potential difference between input terminal and lead-out terminal keeps constant.
It addition, control part 109 preferably control bootstrapping operation, in order to realize correction electricity in emission period
The operation of the secular change in optical element (organic EL element 127).For this purpose, part is controlled
109 operations preferably realizing the secular change in correction electrooptic cell in following state, in a state,
By the driving electric current I in the information kept based on memory transistor 120dsFlow through electrooptic cell (organic EL
Element 127) period in continuously sampling transistor 125 is arranged in nonconducting state, can make
Voltages keep constant between control input terminal and lead-out terminal.Even when organic EL element 127
In current-voltage characteristics occur secular change time, storage capacitor 120 fluorescent lifetime bootstrapping operation also
Control input terminal and the lead-out terminal driving transistor 121 is kept by the storage capacitor 120 of bootstrapping
Between electric potential difference constant, thus all keep constant luminosity in all times.It addition, control portion
Divide 109 preferably to be carried out control to operate to perform threshold correction, for by reference potential (=primary nodal point
Initialization voltage Vofs) it is applied to the input terminal (typical case of input terminal of sampling transistor 125
Son is source terminal) period time in make sampling transistor 125 turn on, and storage capacitor 120 in
Keep the threshold voltage V corresponding to driving transistor 121thVoltage.
If desired, would correspond to signal amplitude VinInformation write storage capacitor 120 before, preferably
The operation of this threshold correction is repeated in multiple horizontal period." if desired for " refer in this case
In the threshold correction period in one horizontal period, corresponding to driving the electricity of the threshold voltage of transistor 121
Pressure can not be adequately retained in storage capacitor 120.Operate repeatedly by performing threshold correction, correspond to
Drive the threshold voltage V of transistor 121thVoltage ensure that storage capacitor 120 in.
It addition, it is furthermore preferred that before threshold correction operates, control part 109 and perform control, in order to
By by reference potential (Vofs) be applied to sampling transistor 125 input terminal period time in make
Sampling transistor 125 turns on, and performs preparatory function (discharge operation and the initialization behaviour of threshold correction
Make),.Before threshold correction operates, initialize control input terminal and the output driving transistor 121
The electromotive force of terminal.More specifically, across storage capacitor 120 on electric potential difference be set equal to or
More than threshold voltage Vth, wherein storage capacitor 120 is connected to drive the control input of transistor 121
Between son and lead-out terminal.
Subsidiary, in the threshold correction in 2Tr/1C drives structure, control part 109 and preferably include to drive
Dynamic sweep test 105, for by scan with the by-line writing sweep test 104 coordinate mutually in the way of select and
Export the first electromotive force VCC_HBe different from the first electromotive force VCC_HThe second electromotive force VCC_LEach to a line
Image element circuit 10, this first electromotive force VCC_HFor making driving electric current IdsThrough electrooptic cell (organic EL
Element 127).Then, it preferably is carried out controlling, in order to would correspond to the first electromotive force VCC_HElectromotive force execute
It is added to drive the power supply terminal of transistor 121 and by reference potential (Vofs) it is applied to sampling transistor
By making sampling transistor 125 turn in period time of 125, and perform threshold correction operation.And,
In threshold correction preparatory function in 2TR drives structure, preferably by would correspond to the second electromotive force
VCC_L(=secondary nodal point initialization voltage Vini) voltage be applied to drive transistor 121 power supply terminal
And by reference potential (Vofs) be applied to sampling transistor 125 period time in make sampling transistor
125 conductings, and control input terminal (the i.e. primary nodal point ND of transistor 121 will be driven1) electromotive force
It is initialized as reference potential (Vofs) and lead-out terminal (the i.e. secondary nodal point of transistor 121 will be driven
ND2) electromotive force be initialized as the second electromotive force VCC_L。
It is furthermore preferred that after threshold correction operates, when by making sampling transistor would correspond to first
Electromotive force VCC_HVoltage be applied to drive transistor 121 and by signal potential (Vofs+Vin) be applied to
In period time of sampling transistor 125 conducting and by signal amplitude VinInformation write storage capacitor
When 120, control part 109 and perform operation so that the correcting value of mobility [mu] that transistor 121 will be driven
It is added in the information of write storage capacitor 120.Now, sampling transistor 125 is preferably made only will to believe
Number electromotive force (Vofs+Vin) be applied in period time on sampling transistor 125 pre-position time
Turning in Duan, the period in this precalculated position is shorter than signal potential (Vofs+Vin) it is applied to sampling transistor
Period time of 125.Will be described in detail 2Tr/1C below and drive the example of the image element circuit 10 in structure.
Image element circuit 10 has the driving transistor substantially formed by n-channel thin-film field-effect transistor.
It addition, image element circuit 10 includes circuit, for suppression due to the long-term degradation of organic EL element
(degradation) the driving electric current I of the organic EL element causeddsChange, i.e. be used for passing through
Correct the change of the I-E characteristic of the organic EL element of the example as electrooptic cell and keep driving
Electric current IdsConstant driving signal homogenization circuit (1), and this image element circuit 10 select by realize
Threshold correction function and mobility calibration function and keep driving electric current IdsConstant drive system, is used for
Prevent owing to driving the change (threshold voltage variation and mobility change) of the characteristic of transistor to cause
Drive the change of electric current.
Characteristic variations (the change of such as threshold voltage, mobility etc. of transistor 121 is driven as suppression
And change) to driving electric current IdsThe method of impact, design (devise) each transistor (drives crystalline substance
Body pipe 121 and sampling transistor 125) driving timing, select the driving of 2TR structure the most as former state simultaneously
Circuit is as driving signal homogenization circuit (1).Image element circuit 10 has 2TR and drives structure, and
Therefore there is fewer number of element and fewer number of circuit.Therefore, image element circuit 10 allows to obtain
Definition that must be higher, and can be without sample video signal V in the case of degeneratingsig, thus can obtain
Outstanding picture quality.
It addition, image element circuit 10 has the characteristic of the connection mode of storage capacitor 120, and formed certainly
For circuit (it is the example driving signal homogenization circuit (2)), as preventing due to organic EL unit
The long-term degradation of part 127 and the circuit of the change driving electric current that causes.Image element circuit 10 is characterised by
Image element circuit 10 has driving signal homogenization circuit (2) realizing bootstrapping function, even as organic EL
During the I-E characteristic generation secular change of element, this bootstrapping function also makes driving current constant (anti-
Only drive the change of electric current).
Subsidiary, image element circuit 10 includes relating to writing gain, bootstrapping gain and mobility correction period
Auxiliary capacitor 310.But, image element circuit 10 includes that auxiliary capacitor 310 is dispensable.Drive
The basic controlling operation of image element circuit 10 is similar to not have the image element circuit 10 of auxiliary capacitor 310
Basic operation.
FET(field-effect transistor) it is used as each transistor, including driving transistor.In this situation
In, drive the gate terminal of transistor as control input terminal, drive source terminal and the drain terminal of transistor
In one (it is assumed hereinafter that driving this in the source terminal of transistor and drain terminal is source terminal) make
For lead-out terminal, and drive another in the source terminal of transistor and drain terminal (it is assumed hereinafter that drive
In the source terminal of transistor and drain terminal this another be drain terminal) as power supply terminal.
Concrete, as shown in Figures 4 and 5, image element circuit 10 includes driving transistor 121 and sampling
Transistor 125(drives transistor 121 and sampling transistor 125 to be each n-channel-types), Yi Jizuo
For launching the organic EL element 127 of the example of the electrooptic cell of light by feeding electric current.Generally, organic
EL element 127 has rectification (current rectifying) characteristic, and therefore by Diode symbol table
Show.Subsidiary, organic EL element 127 has parasitic capacitance Cel.In the drawings, parasitic capacitance CelShown
It is shown as and the form of organic EL element 127(diode) in parallel.
The drain terminal D driving transistor 121 is connected to for applying the first electromotive force VCC_HOr the second electricity
Gesture VCC_LPower line 105DSL.The source terminal S driving transistor 121 is connected to organic EL element
The anode terminal A(of 127 drives source terminal S and the anode tap of organic EL element 127 of transistor 121
Junction point between sub-A is secondary nodal point ND2, and it is set to node ND122).Organic EL element
The negative electrode K of 127 is connected to cathode circuit cath(its electromotive force e.g. negative electrode for applying reference potential
Electromotive force Vcath, or ground (GND)), cathode circuit cath is public to all image element circuits 10.
Subsidiary, cathode circuit cath can be in the monolayer (upper layer circuit) for this cathode circuit cath
Only have circuit, or such as can be provided for cathode circuit being formed in the anode layer of anode line
Auxiliary line, thus the resistance value of cathode circuit reduce.Auxiliary line with grid, arrange or row shape
Formula is arranged on pixel array portion 102(viewing area) in, and auxiliary line is set to and upper layer line
The fixed potential that road is identical.
The gate terminal G of sampling transistor 125 is connected to write scan line from write sweep test 104
104WS.The drain terminal D of sampling transistor 125 is connected to video signal cable 106HS(video signal cable
DTL).The source terminal S of sampling transistor 125 is connected to drive the gate terminal G(sampling of transistor 121
Junction point between the source terminal S and the gate terminal G driving transistor 121 of transistor 125 is first segment
Point ND1, and it is set to ND121).The gate terminal G of sampling transistor 125 is applied to certainly write sweep
The H retouching part 104 effectively writes driving pulse WS.Sampling transistor 125 is alternatively source terminal S and leakage
The connection mode that terminal D exchanges each other.
The drain terminal D driving transistor 121 is connected to from the driving sweep test as electric power scanning device
The power line 105DSL of 105.Power line 105DSL has the property that, i.e. power line 105DSL
Itself have and supply power to the ability driving transistor 121.Drive sweep test 105 select and
Apply the first electromotive force V of high-voltage sideCC_HThe second electromotive force V with low voltage sideCC_LGive and drive transistor
The drain terminal D of 121, the first electromotive force VCC_HCorresponding to supply voltage, the second electromotive force VCC_L(this is second years old
Electromotive force VCC_LAlso referred to as initialization voltage or initial voltage) it is used for the preparatory function before threshold correction.
Image element circuit 10 is by using the first electromotive force VCC_HWith the second electromotive force VCC_LTwo value electric power
Driving pulse DSL drives the drain terminal D side (power circuit side) of transistor 121 to perform threshold value
Preparatory function before correction.Assume the second electromotive force VCC_LRelative to regarding in video signal cable 106HS
Frequently signal VsigReference potential (Vofs) of a sufficiently low.Concrete, the low electricity of power line 105DSL is set
The second electromotive force V on gesture sideCC_LSo that drive the gate source voltage V of transistor 121gs(gate potential Vg
With source electromotive force VsBetween difference) more than drive transistor 121 threshold voltage Vth.Subsidiary, benchmark
Electromotive force (Vofs) it is used for the initialization operation before threshold correction operation, and also for precharge in advance
Video signal cable 106HS.
In this image element circuit 10, when driving organic EL element 127, drive transistor 121
Drain terminal D is applied in the first electromotive force VCC_HAnd the source terminal S driving transistor 121 is connected to organic
The anode terminal A side of EL element 127, thus generally form source follower circuit.
When using this image element circuit 10, by selecting use driving transistor 121 and one to be used for sweeping
The 2TR of other switching transistor (sampling transistor 125) retouched drives structure, and by arranging electricity
Power driving pulse DSL and each switching transistor of ON/OFF timing controlled writing driving pulse WS, stop
The long-term degradation of organic EL element 127 and changing features (the such as threshold value electricity of driving transistor 121
The change of pressure, mobility etc. and change) to driving electric current IdsImpact.
It addition, according in display device 1A of first embodiment, incite somebody to action in each image element circuit 10A
As electric capacity CsubThe auxiliary capacitor 310 of capacity cell be added to node ND122(and drive transistor 121
Source terminal S, storage one terminal of capacitor 120 and the anode terminal A of organic EL element 127
Between junction point).Another terminal (this terminal is referred to as node ND310) institute with auxiliary capacitor 310
The point being connected to is unrelated, the auxiliary capacitor 310 in circuit structure in terms of circuit with organic EL element 127
(parasitic capacitance C of organic EL element 127el) in parallel.By way of example it is assumed that the company of node ND310
Contact be the public cathode circuit cath(of all image element circuits 10 its can be upper layer circuit or boost line
Road), the cathode terminal K of all organic EL element 127 is connected to this cathode circuit.It addition, node
The junction point of ND310 can be such as the power line 105DSL in this level (own stage) (OK), remove this
The power line 105DSL in other level (OK) outside level (OK) or there is the fixing electricity of arbitrary value
Gesture point (including earth potential).Each part as the junction point of node ND310 has the advantage that and shortcoming,
The explanation to these merits and demerits will be omitted below.
Determine the capacitance C of storage capacitor 120CSParasitic capacitance C with organic EL element 127el's
Capacitance Cel, in order to writing gain GinWith bootstrapping gain GbstBetween be balanced, and make each increasing
Yidu is suitable gain.Can be by adjusting the capacitance C of auxiliary capacitor 310subAnd adjust and write gain Gin
With bootstrapping gain Gbst.When utilizing now, it is possible to by relatively adjusting three rgb pixel circuit 10
Between capacitance CsubAnd obtain white balance.Concrete, organic due to each color of R, G and B
The luminous efficiency of EL element 127 is different from each other, so when without auxiliary capacitor 310, in equal driving
Electric current Ids(the most equal signal amplitude VinWhite balance can not be obtained in the case of).Therefore, by not
Different signal amplitude V is provided with colorinAnd obtain white balance.On the other hand, by relatively adjusting three
The capacitance C of the auxiliary capacitor 310 between individual rgb pixel circuit 10sub, even in equal driving
Electric current IdsIn the case of also can obtain white balance.Furthermore it is possible in the situation not affecting threshold correction operation
Under by add auxiliary capacitor 310 adjust correction mobility [mu] needed for time.Even work as image element circuit
When the driving of 10 quickly increases, it is possible to enter correction time by using auxiliary capacitor 310 to adjust mobility
The mobility correction that row is enough.
[structure that first embodiment is exclusive]
It is different from the common thin film transistor (TFT) without backgate terminal, at control input terminal (gate terminal)
Outside also have and can control transistor characteristic and (in this case, increase or reduce threshold voltage Vth)
The transistor of control terminal (being referred to as transistor characteristic control terminal after this control terminal) be used as
Image element circuit 10X according to the first comparative example and every according in the image element circuit 10Y of the second comparative example
Individual transistor.The exemplary of the transistor with " transistor characteristic control terminal " is back of the body gate type thin film
Transistor or MOS transistor, as shown in Figure 3 B.Subsidiary, at the picture according to the first comparative example
In element circuit 10X, each transistor characteristic of sampling transistor 125 and driving transistor 121 controls
Terminal is connected to ground potential points (minimum voltage used in image element circuit 10).Comparing according to second
In the image element circuit 10Y of example, the transistor characteristic control terminal of sampling transistor 125 is connected to earth potential
Point (minimum voltage used in image element circuit 10), but drive the transistor characteristic control of transistor 121
Terminal processed is connected to drive the source terminal of transistor 121.In the case of the second comparative example, worry reliable
Property be adversely affected, this is because when turn off drive transistor 121 time (by by the second electromotive force VCC_L
It is applied to extinguishing (quenching) time of drain terminal), occur the drain terminal driving transistor 121 to become
The reverse bias condition lower than base (base) electromotive force (back gate voltage).Although being not described in detail, but this
It is due to the fact that when turning off driving transistor 121, drives the drain voltage of transistor in short-term
In drop to the second electromotive force VCC_L, but when parasitic capacitance C of organic EL element 127elAnd auxiliary
Electric capacity 310(Csub) electric discharge time, source electromotive force and base electromotive force certain time to be spent realize voltage decline.
On the other hand, first embodiment includes the transistor characteristic control with Characteristics Control sweep test 621
Part 620A processed, and first embodiment is configured to special from transistor Characteristics Control part 620A(
Property control sweep test 621) " predetermined control electromotive force " be applied to the transistor of sampling transistor 125
Characteristics Control terminal.Subsidiary, in the first embodiment, as at the image element circuit according to the second comparative example
In 10Y, the transistor characteristic control terminal of transistor 121 is driven to be connected to drive the source of transistor 121
Terminal.And, as in the image element circuit 10X according to the first comparative example, drive the crystalline substance of transistor 121
Body pipe Characteristics Control terminal may be connected to ground potential points.
As will be described in detail later, " predetermined control electromotive force " is the pulse for suppressing luminance shortage phenomenon
The control voltage of form.Owing to luminance shortage phenomenon is relevant with signal write, so substantially utilizing use
The Characteristics Control that the structure of the signal relevant with signal write controls part 620A as transistor characteristic is swept
Retouch the structure of part 621.Such as, Characteristics Control sweep test 621 produces corresponding to transistor characteristic control
The high/low scanning impulse of signal Vb processed, makes scanning impulse carry out level conversion, and then passes through spy
Property control the output of scan line 621VB there is the transistor characteristic control signal of appropriate level Vb_H and Vb_L
Vb。
" signal relevant with signal write " uses the signal shown in other embodiments to be described
Canonical representation, but it is not limited to these signals.In other words, it is believed that the structure of first embodiment applies to
The general construction of each " signal relevant with signal write ", but to be described other is implemented
Example is the form of the object lesson of " signal relevant with signal write ".
[operation of image element circuit]
Figure 10 is for helping explain signal amplitude V by by-line systeminInformation write storage capacitor
The sequential chart (perfect condition) of operation when 120, it is as about image element circuit 10(comparative example and first
Each in embodiment) the example of driving timing.What Figure 10 was shown on axle common time writes scan line
The potential change of 104WS, the potential change of power line 105DSL and the electricity of video signal cable 106HS
Gesture changes.Figure 10 also illustrates the gate potential V driving transistor 121 abreast with these potential changegWith
Source electromotive force VsChange.Basic, with the delay of a horizontal sweep period to every row write scan line
104WS and power line 105DSL performs similar driving.
The electricity of organic EL element 127 is flow through by the timing controlled of pulse (signal in such as Figure 10)
The value of stream.In the timing example of Figure 10, by driven by power pulse DSL being arranged to the second electricity
Gesture VCC_LAnd after performing extinguishing and the initialization of node ND122, by by sampling transistor 125
It is arranged on open state to initialize node ND121, simultaneously by primary nodal point initialization voltage VofsIt is applied to
Video signal cable 106HS, and in a state driven by power pulse DSL is arranged to the first electromotive force
VCC_H, thus carries out threshold correction.Hereafter, sampling transistor 125 is arranged on off status, and
By video signal VsigIt is applied to video signal cable 106HS.In this state, sampling transistor 125
It is arranged on open state, thus is simultaneously written signal and carries out mobility correction.After write signal,
Light emission is started when sampling transistor 125 is arranged on off status.Therefore by the phase contrast of pulse it is
Mobility correction, threshold correction etc. control to drive.When driving display device 1A according to first embodiment
In image element circuit 10A time, by transistor characteristic control signal Vb based on " relevant with signal write
Signal " (mode associated with signal writing operation) pulsed drive (pulse-drive) sample crystal
The backgate terminal of pipe 125.
This operation described in detail below, attention points to threshold correction and mobility correction.At pixel electricity
In road 10, for driving timing, first sampling transistor 125 is in response to executing from writing scan line 104WS
Add writes driving pulse WS and turns on, the video signal applied from video signal cable 106HS with sampling
VsigAnd by video signal VsigIt is maintained in storage capacitor 120.Hereinafter, for the ease of introducing and reason
Solve, except as otherwise noted, will be by by signal amplitude VinInformation table be shown as write, be maintained at or adopt
Sample concisely describes, for example, it is assumed that writing gain is 1(ideal value in storage capacitor 120).
When writing gain less than 1, corresponding to signal amplitude VinSize and with the information of multiplied by gains rather than
Signal amplitude VinItself, be maintained in storage capacitor 120.
For the driving timing of image element circuit 10, when by video signal VsigSignal amplitude VinInformation
When writing storage capacitor 120, performing by-line and drive, from the angle of scanning continuously, it is simultaneously by a line
Video signal transmission to the video signal cable 106HS of each row.Concrete, at the picture utilizing 2TR to construct
Driving timing in element circuit 10 carries out, in the basic conception of threshold correction and mobility correction, first existing
In the 1H period, video signal VsigThere is reference potential (V based on timesharingofs) and signal potential
(Vofs+Vin).Especially, it is assumed that video signal VsigAt reference potential (Vofs) place, as invalid
The period of period is the first half parts of a horizontal period, and video signal VsigAt video electromotive force
(Vsig=Vofs+Vin) place, the second half parts that as period of effectual time are a horizontal period.
When a horizontal period is divided into the first half parts and the second half parts, horizontal period typically by
It is divided into the half of substantially equal period.But, this is dispensable.The second half parts can be longer than the first half portions
Point, or contrary, the second half parts can be shorter than the first half parts.
Assume to be additionally operable to threshold correction and mobility correction for the driving pulse WS that writes of signal write, and
And write driving pulse WS by twice activation in the 1H period and open sampling transistor 125.First
Individual opening carries out threshold correction in (on) timing, and performs signal write in second Open Timer simultaneously
Correct with mobility.Hereafter, transistor 121 is driven to receive from electricity at the first electromotive force (high potential side)
The electric current of source line 105DSL, and, (right according to the signal potential being maintained in storage capacitor 120
Should be in the video signal V in effectual timesigThe electromotive force of electromotive force) electric current I will be drivendsIt is fed through organic
EL element 127.Subsidiary, substitute twice activation in the 1H period and write driving pulse WS, Ke Yi
While keeping the open state of sampling transistor 125, the electromotive force of video signal cable 106HS is arranged letter
Number electromotive force (=Vofs+Vin) in order to control the brightness in organic EL element 127.
Such as, at video signal VsigInactive time period in, vertical driving section 103 output write driving arteries and veins
Rush WS as control signal, be used for making sampling transistor 125 at power line 105DSL at the first electromotive force
And video signal cable 106HS is at reference potential (Vofs) period time in turn on, thus by correspondence
In the threshold voltage V driving transistor 121thVoltage be maintained at storage capacitor 120 in.This operation is real
Existing threshold correction function.This threshold correction function can offset the threshold voltage V driving transistor 121thShadow
Ringing, this threshold voltage changes between image element circuit 10.
Vertical driving section 103 is preferably by sampled signal amplitude VinBefore, in multiple horizontal period
It is repeatedly carried out threshold correction operation, makes the threshold voltage V corresponding to driving transistor 121thVoltage
It is maintained at definitely in storage capacitor 120.Guarantee sufficiently long by threshold correction operation is performed a plurality of times
Write the time.This makes to can ensure that the threshold voltage V that would correspond to drive transistor 121 in advancethVoltage protect
Hold in storage capacitor 120.
Keep corresponding to threshold voltage VthVoltage for offset drive transistor 121 threshold voltage
Vth.Therefore, even change between image element circuit 10 as the threshold voltage vt h driving transistor 121
Time, it is also possible to it is completely counterbalanced by the change of each image element circuit 10, thus it is (that is, aobvious to improve image conformity
The uniformity of the luminosity on the whole screen of showing device).Especially, it is possible to prevent when signal potential is used
The brightness flop occurred is tended to when low gray scale (gradation).
Preferably, vertical driving section 103 video signal V before threshold correction operatessigInvalid time
In Duan by power line 105DSL at the second electromotive force and video signal cable 106HS at reference potential
(Vofs) period time in activate write in driving pulse this example of WS(as H-level) and make sampling brilliant
Body pipe 125 turns on, and subsequently will write driving heartbeat pulse WS be maintained at effectively (active) H
While power line 105DSL is arranged to the first electromotive force.
Therefore, the second electromotive force V is reset at source terminal SCC_L(electric discharge period C=secondary nodal point initializes
Period) and drive the gate terminal G of transistor 121 to reset to basis reference electromotive force (Vofs) (initialize
Period D=primary nodal point initialization period) after, start threshold correction operation (threshold correction period E),
This second electromotive force VCC_LIt is sufficiently below reference potential (Vofs).This resetting gate electromotive force and the behaviour of source electromotive force
Make the threshold correction operation that (initialization operation) makes it possible to reliably perform subsequently.Electric discharge period C and
Initialization period D will be collectively known as the threshold correction preparation period (=pretreatment period), be used for initializing
Drive the gate potential V of transistor 121gWith source electromotive force Vs。
In threshold correction period E, the electromotive force of power line 105DSL the second electromotive force from low potential side
VCC_LThe the first electromotive force V being converted on high potential sideCC_H, thus drive the source electromotive force V of transistor 121s
Begin to ramp up.Concrete, drive the gate terminal G of transistor 121 to be maintained at video signal VsigBenchmark
Electromotive force (Vofs), and drain current flows is until driving the electromotive force V of the source terminal S of transistor 121s
The rear drive transistor 121 of rising is truncated.When driving transistor 121 to be truncated, drive transistor
The source electromotive force Vs of 121 becomes " Vofs-Vth”.In threshold correction period E, in order to allow leakage current only
Flow through storage capacitor 120 side and (work as CCS<<CelTime) and stop drain current to flow to organic EL unit
Part 127 side, arranges the electromotive force V of the public ground circuit cath of all pixelscath, in order to block organic EL
Element 127.
Due to by diode and parasitic capacitance CelParallel circuit represent the equivalence of organic EL element 127
Circuit, if so " Vel≤Vcath+VthEL" (if the leakage (leakage) of i.e. organic EL element 127
Electric current drives the electric current of transistor 121 much smaller than flowing through), drive the drain current I of transistor 121dsQuilt
For to storage electric capacity 120 and parasitic capacitance CelCharging.As a result, the anode tap of organic EL element 127
The voltage V of sub-Ael(that is, the electromotive force of node ND122) rises in time.Then, as node ND122
Electromotive force (source electromotive force Vs) and voltage (the gate potential V of node ND121gElectric potential difference between) is just
Become threshold voltage VthTime, drive transistor 121 to change to off status, drain current I from open statedsStop
Fluid stopping is moved, and the threshold correction period terminates.That is, after special time, transistor 121 is driven
Gate source voltage VgsUse threshold voltage Vth。
In this case, can only perform threshold correction to operate once.But, this is dispensable.Can
Repetitive operation threshold correction repeatedly, wherein with horizontal period for processing the cycle.Such as, preferably,
By a threshold correction, would correspond to threshold voltage VthVoltage write storage capacitor 120, this is deposited
Storage capacitor 120 is connected between the gate terminal G and source terminal S of driving transistor 121.But, threshold
Value correction period E lasts till will write driving arteries and veins from by the moment writing driving pulse WS and arranging effective H
Rush WS and return to the moment of invalid L.When this period of insufficient guarantee, this period is reaching corresponding
In threshold voltage VthVoltage before terminate.Threshold correction operation is preferably repeated several times solve this and ask
Topic.The timing of the most not shown this threshold correction operation.
When threshold correction operation is performed a number of times, a horizontal period is the process week of threshold correction operation
Phase, this is because performed initialization operation before threshold correction operates, this initialization operation is at a water
At ordinary times the first half parts of section apply reference potential (V by video signal cable 106HSofs) and will
Source electromotive force arranges the second electromotive force VCC_L.The threshold correction period is necessarily shorter than a horizontal period.Therefore,
Owing to storing the capacitance C of capacitor 120CS, the second electromotive force VCC_LMagnitude relationship and other factors,
There may be situations below: in a short period of time of threshold correction operation, corresponding to threshold voltage Vth
Precise voltage may not be entirely held in storage capacitor 120 in.Threshold correction is preferably performed a plurality of times
Operation processes this situation.I.e., preferably by sampled signal amplitude V in storage capacitor 120in
In multiple horizontal period, repeat threshold correction operation before (signal write), would correspond to assuredly
Drive the threshold voltage V of transistor 121thVoltage be maintained at storage capacitor 120 in.
Image element circuit 10 also has mobility calibration function in addition to threshold correction function.Concrete, in order to
It is in video signal V at video signal cable 106HSsigEffectual time in signal potential (Vofs+Vin)
Being arranged in conducting state by sampling transistor 125 in period time at place, vertical driving section 103 is only
The driving pulse of writing being applied to write scan line 104WS for the period shorter than above period time keeps
For effectively (being H-level in the present example).In this short period of time, drive transistor 121 at signal
Electromotive force (Vofs+Vin) be applied to drive transistor 121 control input terminal state in, to organic
Parasitic capacitance C of EL element 127elCharge with storage capacitor 120.When corresponding to signal amplitude Vin
Information be maintained at storage capacitor 120 in time, by suitably arrange write having of driving pulse WS
The effect period (this period is also sampling periods and mobility correction period), transistor can be driven simultaneously
The correction of the mobility [mu] of 121.By horizontal driving section 106 by signal potential (Vofs+Vin) actual
It is applied to video signal cable 106HS and the period writing driving pulse WS and being set to effective H is set
It is set to signal amplitude VinWrite the period of storage capacitor 120 (when this period will also referred to as sample
Section).
Concrete, in the driving timing of image element circuit 10, at power line 105DSL in high potential side
First electromotive force VCC_HAnd video signal Vsig(at signal amplitude V in effectual timeinPeriod in)
Period in, activate write driving pulse WS.I.e. as a result, define mobility timing by a scope
Section (and sampling periods), in this range, the electromotive force of video signal cable 106HS is video signal Vsig
Effectual time in signal potential (Vofs+Vin) period in time width with write driving pulse WS's
Effectual time overlaps each other.Concrete, it is set to owing to writing the effectual time width of driving pulse WS
Narrower, in order to be contained in video signal cable 106HS and be in the time width of signal potential, so moving
Shifting rate is determined by writing driving pulse WS correction time.More accurately, (and adopt mobility correction time
The sample period) it is to rise and sampling transistor 125 opens (turn on) to together from writing driving pulse WS
One writes driving pulse WS declines and sampling transistor 125 turns off time of (turn off).
Concrete, in sampling periods, sampling transistor 125 is arranged in conducting (opening) state, its
The gate potential V of middle driving transistor 121gAt signal potential (Vofs+Vin).Therefore, writing and migrating
In rate correction period H, drive electric current IdsIt is fixed on signal electricity at the gate terminal G driving transistor 121
Gesture (Vofs+Vin) state in flow through driving transistor 121.Signal amplitude VinInformation to be added to drive
The threshold voltage V of dynamic transistor 121thOn mode keep.As a result, the threshold value electricity of transistor 121 is driven
Pressure VthChange be always eliminated, it means that carried out threshold correction.As the result of threshold correction,
The gate source voltage V kept by storage capacitor 120gsIt is " Vsig+Vth”=“Vin+Vth”.It addition,
Sampling periods carries out mobility correction simultaneously.Therefore sampling periods be also mobility correction the period (write and
Mobility correction period H).
Made V at that timethELFor the threshold voltage of organic EL element 127, carry out " Vofs-Vth< VthEL"
When arranging, organic EL element 127 is arranged in reverse biased (reverse-biased) state and has
Machine EL element 127 is the state of blocking (high impedance status).Therefore, organic EL element 127 is not launched
Light, and present simple capacitance characteristic rather than diode characteristic.Therefore, driving transistor 121 is flow through
Drain current (drive electric current Ids) it is written to electric capacity " C=CCS+Cel", this electric capacity " C=CCS+Cel”
By the electric capacity C by storage capacitor 120CSParasitic capacitance (equivalent capacity) with organic EL element 127
CelElectric capacity CelCombine and obtain.Therefore, the drain current of transistor 121 is driven to flow to organic EL unit
Parasitic capacitance C of part 127elIn, and therefore start to charge up.As a result, the source electromotive force of transistor 121 is driven
VsRise.
In the sequential chart of Figure 10, this rising Δ V represents.As the result of threshold correction, this rising
(i.e. as the potential correction value Δ V of mobility correction parameter) is by from being maintained in storage capacitor 120
Gate source voltage " Vgs=Vin+VthDeduct in ", and " Vgs=Vin+Vth-Δ V ", it means that apply negative
Feedback.The source electromotive force Vs driving transistor 121 is now by from gate potential Vg(=VinGuarantor is deducted in)
Hold the voltage " V in storage capacitorgs=Vin+Vth-Δ V " and the value "-V that obtainsth+ΔV”。
Therefore, in the driving timing of image element circuit 10, writing with in mobility correction period H, holding
Row signal amplitude VinSampling and for correcting the degenerative amount of Δ V(or the mobility of mobility [mu]
Correction parameter) adjustment.Write sweep test 104 adjustable to write and the time width of mobility correction period H
Degree.Therefore, it can optimize and drive electric current IdsDegenerative amount.
Potential correction value Δ V is Ids·t/Cel.Even if when due to the mobility [mu] in each image element circuit 10
Change and cause drive electric current IdsDuring change, also obtain corresponding to the driving in each image element circuit 10
Electric current IdsPotential correction value Δ V.Therefore, the change of the mobility [mu] in each image element circuit 10 can quilt
Correction.Concrete, as signal amplitude VinTime fixing, the mobility [mu] driving transistor 121 is the biggest, electricity
The absolute value of gesture correction value delta V is the biggest.In other words, mobility [mu] is the biggest, and value Δ V is the biggest for potential correction,
Thus the change of the mobility [mu] in each image element circuit 10 can be removed.
Image element circuit 10 also has bootstrapping function.Concrete, at signal amplitude VinInformation be maintained at
In stage in storage capacitor 120, write sweep test 104 cancellation and write driving pulse WS to writing scanning
The applying of line 104WS (that is, will write driving pulse WS invalid L(is set low)), thus will sampling
Transistor 125 is arranged on nonconducting state, and therefore the gate terminal G of transistor 121 will be driven from regarding
Frequently holding wire 106HS electrically disconnects (emission period I).Before emission period I, horizontal driving section
The electromotive force of video signal cable 106HS is returned to reference potential (V at suitable subsequent point in time by 106ofs).
The luminance of organic EL element 127 lasts till that (m+m '-1) is till the horizontal sweep period.
This terminates formation (n, m) light emission operation of the organic EL element 127 of sub-pixel.Hereafter, enter
To next frame (or field), again repeat threshold correction preparatory function, threshold correction operation, mobility school
Just operating and light emission operation.
In emission period I, the gate terminal G and video signal cable 106HS of transistor 121 is driven to disconnect.
Owing to eliminating signal potential (Vofs+Vin) it is applied to drive the gate terminal G of transistor 121, so
Drive the gate potential V of transistor 121gBecome able to rise.Storage capacitor 120 is connected to drive crystal
Between the gate terminal G and source terminal S of pipe 121.Bootstrapping behaviour is performed by the effect of storage capacitor 120
Make.Assume that bootstrapping gain is 1(ideal value), then drive the gate potential V of transistor 121gWith driving crystal
The source electromotive force V of pipe 121sThe association of change operation ground, thus gate source voltage VgsCan keep constant.Now,
Flow through the driving electric current I driving transistor 121dsFlow to organic EL element 127, and organic EL element
The anode potential of 127 is according to driving electric current IdsAnd rise.Assume that this ascending amount is Vel.Along with source voltage
The rising of Vs, the final reverse bias condition eliminating organic EL element 127.Therefore, organic EL unit
Part 127 is actually with the driving electric current I being flowed in organic EL element 127dsStart to launch light.
By by " Vsig+Vth-Δ V " or " Vin+Vth-Δ V " it is updated to aforesaid expression transistor characteristic
Formula (1) in, can will drive electric current IdsWith gate source voltage VgsRelational representation be formula (5A)
Or formula (5B) (two formula will be collectively referred to as formula (5)).
Ids=k·μ·(Vsig–Vofs–ΔV)2 (5A)
Ids=k·μ·(Vin–Vofs–ΔV)2 (5B)
Formula (5) display threshold voltage VthItem be eliminated, and be applied to organic EL element 127
Driving electric current Ids be not dependent on drive transistor 121 threshold voltage Vth.I.e., such as work as VofsIf
Put when 0 volt, flow through the electric current I of organic EL element 127dsWith by from control organic EL element
The video signal V of the brightness of 127sigValue in deduct secondary nodal point ND2(drive transistor 121 source
Terminal) the potential correction value Δ V at place and the value that obtains square proportional, potential correction Δ V-value is originated
In the mobility [mu] driving transistor 121.In other words, the electric current I of organic EL element 127 is flow throughdsNo
Depend on the threshold voltage V of organic EL element 127thELOr drive the threshold voltage V of transistor 121th。
That is, organic EL element 127 light quantity (brightness) launched is not by the threshold value electricity of organic EL element 127
Pressure VthELOr drive the threshold voltage V of transistor 121thImpact.(n, m) organic EL unit
The brightness of part 127 corresponds to electric current IdsValue.
It addition, the transistor 121 that drives of high mobility μ has a bigger potential correction value Δ V, and because of
This has the gate source voltage V of smaller valuegs.Therefore, even if when the mobility [mu] in formula (5) is bigger
Value time, (Vsig-Vofs-Δ V)2Value the least, thus recoverable drain current Ids.That is, even if existing
Drive transistor 121 mobility [mu] different from each other in the case of, as video signal VsigWhen being worth identical,
Drain current IdsThe most essentially identical.As a result, flow through organic EL element 127 and control organic EL element
The electric current I of the brightness of 127dsHomogenized.That is, the brightness flop of organic EL element 127 can be corrected,
This change is caused by the change (and change of k) of mobility [mu].
It addition, storage capacitor 120 be connected to drive transistor 121 gate terminal G and source terminal S it
Between, and perform bootstrapping operation when emission period starts due to the effect of storage capacitor 120.Drive
The gate potential V of dynamic transistor 121gWith source electromotive force VsRise, and simultaneously drive the gate-source of transistor 121
Voltage " Vgs=Vin+Vth-Δ V " keep constant.As the source electromotive force V driving transistor 121sBecome
“-Vth+ΔV+Vel" time, gate potential Vg becomes " Vin+Vel”.Now, owing to driving transistor 121
Gate source voltage VgsConstant, so driving transistor 121 that (constant current is driven electric current Ids) feed
By organic EL element 127.As a result, the electromotive force (=joint of the anode terminal A of organic EL element 127
The electromotive force of some ND122) rise to a voltage so that as the driving electric current I in saturationdsElectricity
Stream can flow through organic EL element 127.
The long fluorescent lifetime of organic EL element 127 changes the I-V characteristic of organic EL element 127.Therefore,
The electromotive force of node ND122 changes over time.But, even if when due to organic EL element
The long-term degradation of 127 and when causing the anode potential change of this organic EL element 127, store capacitor
The 120 gate source voltage Vgs kept also are constantly maintained at " Vin+Vth-ΔV”.Transistor 121 is driven to make
Operate for constant-current source.Therefore, though when organic EL element 127 I-V characteristic over time and
Change, and drive the source electromotive force V of transistor 121sDuring respective change, owing to driving transistor 121
Gate source voltage VgsConstant (≈ V is kept by storage capacitor 120in+Vth-Δ V), therefore flow through organic EL
The electric current of element 127 is the most constant, and the luminosity of therefore organic EL element 127 also keeps constant.
It practice, bootstrapping gain is less than " 1 ".Therefore, gate source voltage VgsFrom " Vin+Vth-Δ V " reduce,
But still keep the gate source voltage V corresponding to gain of bootinggs。
As described above, when design driven timing, image element circuit 10 automatically forms threshold correction electricity
Road and mobility correcting circuit.Concrete, in order to stop the characteristic variations driving transistor 121 (originally to be shown
Example is threshold voltage VthChange with carrier mobility μ) to driving electric current IdsImpact, pixel
Circuit 10 is used as to drive signal homogenization circuit, for by corrected threshold voltage VthAnd carrier mobility
The impact of rate μ and keep driving current constant.Not only can perform bootstrapping operation, can also carry out threshold correction
Operation and mobility correct operation.Therefore, by corresponding to threshold voltage VthWith correct for mobility
The gate source voltage V that the Voltage Cortrol of potential correction value Δ V is kept by bootstrapping operationgs.Therefore, organic
The luminosity of EL element 127 is not driven the threshold voltage V of transistor 121thOr mobility [mu]
Change impact, do not affected by the long-term degradation of organic EL element 127.As a result, display device 1
Can correspond to incoming video signal Vsig(signal amplitude Vin) stable gray scale show, and because of
This provides the image of high image quality.
It addition, the source follower circuit of transistor 121 can be driven to form image element circuit by using n-channel-type
10.Therefore, even if organic EL of the anode having in present case and cathode electrode ought be used as former state
During element 127, image element circuit 10 also can drive organic EL element 127.It addition, image element circuit 10 can
Formed merely with n-channel transistor, including driving transistor 121, driving transistor 121 outer part
The sampling transistor 125 etc. divided.Therefore, the reduction of transistor manufacturing cost can be obtained.
[there is the reason of luminance shortage phenomenon]
When sampling periods and mobility calibrate the signal writing operation in the period, how to use larger quantities
And higher fidelity (fidelity) (having linear) would correspond to signal potential V (magnitude)in
Information write storage capacitor 120 in extremely important." larger quantities " is write gain G by so-calledinFixed
Justice.In order to about video signal VsigSignal potential VinGuarantee brightness efficiently, drive electric current Ids
Along with the gate potential V driving transistor 121gRising and flow and source electromotive force VsTime in write
(the low source electromotive force V of transistor 121 is i.e. driven in the write time in the case of not risingsIn the case of),
Preferably by electric capacity CCSStorage capacitor 120 voltage and the video signal V that keepsigRatio (write gain
Gin) be configured to the biggest.Use the electric capacity C of storage capacitor 120CS, driving transistor 121
Parasitic capacitance C121 formed at gate terminal GgsElectric capacity Cgs, and the parasitism of organic EL element 127
Electric capacity Cel, can by this case write gain GinIt is expressed as
Gin=C2/(C1+C2)=(CCS+Cgs)/{ (CCS+Cgs)+Cel}
When considering auxiliary capacitor 310, by CelBecome " Cel+Csub" be sufficient for.
Parasitic capacitance C121gsElectric capacity CgsIt is believed that less than the electric capacity C of storage capacitor 120CSWith organic
Parasitic capacitance C of EL element 127el.Therefore, when parasitic capacitance C of organic EL element 127elFully
Electric capacity C more than storage capacitor 120CSTime, or in other words, when being added to drive transistor 121
Capacitance between gate terminal G and source terminal S is (in this case for the electric capacity C of storage capacitor 120CS)
Maybe when being added to drive the source terminal S(i.e. anode terminal of organic EL element 127 of transistor 121 during reduction
A) and the cathode terminal K of cathode circuit cath(organic EL element 127) between capacitance (at this
It situation is parasitic capacitance C of organic EL element 127el) increase time, write gain GinUnlimited near " 1 ".
Therefore, closer to signal potential VinThe information of voltage of size can be written to store capacitor 120.
On the other hand, it has been found that " higher fidelity (having linear) " is needed to consider back-gate effect
(also referred to as substrate bias effect (substrate bias effect)).Concrete, when use has backgate effect
The field-effect transistor answered is as write transistor TRWTime, there is following phenomenon: even if when inputting high video
When signal level is to obtain high brightness, it is also possible to the brightness corresponding to incoming video signal level can not be obtained.
Such as assume to use MOS transistor.Generally, in image element circuit 10, the base electromotive force of MOS transistor
(base voltage) (back gate potential) is disposed substantially in emission state the minimum voltage used.Such as, as
In first comparative example of Fig. 4 and Fig. 5, apply the minimum voltage (earth potential) as fixed potential to base
Electromotive force.In this case, necessary luminosity is the biggest, and gate potential and source electromotive force need the highest, and
Base-source voltage V between source terminal and cardinal extremity (backgate terminal)bsIncrease the most.But, this
In situation, along with base-source voltage VbsIncrease, due to the threshold value of substrate bias effect sampling transistor 125
Voltage VthIncrease, and hence in so that write is difficult, and work on the direction of suppression brightness.
Therefore luminance shortage phenomenon occurs.Luminance shortage phenomenon is different according to gray scale (gradation), this meaning
Taste has γ characteristic (linearly losing) for each gray scale.In the case of colour shows, worry tone
Skew.In order to eliminate luminance shortage phenomenon, need to increase further the gate source voltage of sampling transistor 125
Vgs.As a result, video signal VsigVoltage need be set higher.
[as the method for the countermeasure measuring luminance shortage phenomenon]
The present embodiment is by by transistor characteristic control signal based on " signal relevant with signal write "
Vb is applied to the transistor characteristic control terminal of sampling transistor 125, eliminates and is caused by back-gate effect
Luminance shortage phenomenon, and thus improve transistor characteristic when signal writes." improvement transistor characteristic "
Refer to such as improve write capability, and reduce threshold voltage Vth。
Figure 11 and 12 is to aid in explaining the former of the countermeasure for the luminance shortage phenomenon caused by back-gate effect
The figure of reason.Figure 11 is to aid in explaining transistor characteristic (Vgs-IdsCharacteristic) dependent to substrate electromotive force
Figure.Figure 12 is to aid in explaining the sequential chart of the method driving the image element circuit according to first embodiment, notes
Power points to transistor characteristic control signal Vb.
As it is known, due to back-gate effect, back of the body gate type thin film transistor or the transistor of MOS transistor
Characteristic is different.Such as, usually, MOS transistor be generally taken as there is bipolar transistor three
Terminal device.But, more accurately, MOS transistor also should be taken as four-terminal device, this is because
Form source region and the substrate in drain region or trap should be taken as control terminal (transistor characteristic control terminal).
When transistor characteristic control signal Vb(is also referred to as back gate voltage, substrate electromotive force or base electromotive force) apply
To time between source terminal and transistor characteristic control terminal (such as substrate (also known as body)), can control
Transistor characteristic.Back gate voltage is typically applied to as negative voltage, thus diode is in the state of blocking.Such as,
When applying back gate voltage, tightly it is located immediately at the depletion layer under source and leakage raceway groove and is changed, as in two poles
As in pipe, and the electromotive force of semiconductor surface changes.Therefore, according to whether be applied with back gate voltage,
Change the electric charge in depletion layer.As shown in Figure 11, transistor characteristic (Vgs-IdsCharacteristic) it is changed.
Therefore, threshold voltage VthIt is changed.It is known that when considering back-gate effect, threshold voltage VthAbout to carry on the back
The speed of 1/2 power of gate voltage increases.Subsidiary, although in simple theory, threshold voltage Vth
Increase with the speed of 1/2 power of about back gate voltage, even if generally this increase being regarded as linearly increasing, real
In trampling, also there is no problem.
As shown in Figure 11, along with substrate electromotive force (that is, transistor characteristic control signal Vb) rises,
Threshold value declines, such that it is able to promote by the sampling transistor 125 write to signal voltage.That is, as
In Figure 12, transistor characteristic control signal Vb based on " signal relevant with signal write " is sufficient to
Enough at least in time for writing signal (specially adjacent after write starts certain (certain) period)
Reduce the threshold voltage V of sampling transistor 125th." adjacent certain period after write starts " no
Need to be that video signal writes whole period (sampling periods in first embodiment and the mobility processing step
The correction period), and refer to its threshold voltage V that be enough to change sampling transistor 125th, in order to from opening
The threshold voltage V of sampling transistor 125 is reduced during this certain period begunth." certain period " be
Voltage corresponding to the amplitude of video signal is written to store the just foot of the period before capacitor 120 substantially
Enough.
In each image element circuit 10A, transistor characteristic controls part 620A and is configured to arrange sampling crystalline substance
Transistor characteristic control signal Vb of body pipe 125.When during the certain period starting from signal write
When improving transistor characteristic control signal Vb of sampling transistor 125, threshold voltage V can be madethIt is lower,
Such that it is able to promote by the sampling transistor 125 write to signal voltage.Input high video level
To obtain high brightness, and by the way of associating with the input operation with high video level similarly
Improve transistor characteristic control signal Vb for sampling transistor 125, change threshold voltage Vth.From
And can suppress or eliminate luminance shortage phenomenon.Structure described above can eliminate be difficult to produce highlighted
Degree (write difficulty) or the problem needing to arrange higher signal voltage.
[the second embodiment]
Figure 13 and 14 is to illustrate the image element circuit 10B according to the second embodiment and include this image element circuit
The figure of the form of the display device of 10B.Pixel array portion 102 has according to the second embodiment
The display device of image element circuit 10B will be referred to as display device 1B according to the second embodiment.Figure 13 shows
Go out (each pixel) essential structure.Figure 14 illustrates specific configuration (whole display device).Figure 15
Being to aid in explaining the sequential chart of the operation of the second embodiment, attention points to transistor characteristic control signal Vb.
As shown in figure 13 and figure 14, the second embodiment has transistor in each image element circuit 10B
Characteristics Control part 620B.Transistor characteristic controls part 620B and has capacity cell 622, this electric capacity
Element 622 is connected to transistor characteristic control terminal (backgate terminal) and the control of sampling transistor 125
Between input terminal processed (gate terminal).Characteristics Control sweep test 621 is not necessarily.Subsidiary,
In fig. 13 by resistive element RBGRepresent the line resistance of the backgate of sampling transistor 125.Transistor
Characteristics Control part 620B may also include and is applied to transistor characteristic control for adjustment by capacity cell 622
The time constant adjustment member 624 of the time constant of the signal of terminal processed, but time constant adjustment member
624 not necessarily.As an example, time constant adjustment member 624 has resistive element 625, this electricity
Resistance element 625 is connected to the transistor characteristic control terminal of sampling transistor 125 and for applying transistor
Between the circuit of characteristic control signal Vb.In fig. 13, resistive element 625 is arranged on capacity cell 622
And between the backgate terminal of sampling transistor 125.But, resistive element 625 may be provided at capacity cell
Between 622 and the gate terminal of sampling transistor 125.
About the transistor characteristic control how producing the luminance shortage phenomenon caused for suppression by back-gate effect
Signal Vb processed, controls part 620A according to the transistor characteristic of first embodiment and uses " with signal write
Relevant signal ", and it be also possible to use arbitrary signal, as long as the signal relevant with signal write is used i.e.
Can.On the other hand, the second embodiment use writes arteries and veins for what the ON/OFF performing sampling transistor 125 controlled
Rush the WS object lesson as " signal relevant with signal write ".In a second embodiment, electric capacity
Element 622 is added between the backgate of sampling transistor 125 and grid line (writing scan line 104WS), from
And coupling (coupling) voltage writing a signal to the rising edge of the write pulse WS of time is input to base electricity
Gesture, and thus promote by the sampling transistor 125 write to signal voltage.
As shown in Figure 15, when write pulse WS is coupled to backgate terminal by capacity cell 622, right
In from sampling periods and mobility correct the period start certain period, transistor characteristic control signal Vb
Can increase.Therefore, the threshold voltage V of sampling transistor 125 is changedthTo become lower, such that it is able to promote
Enter by the sampling transistor 125 write to signal voltage.Subsidiary, due to writing of time for writing signal
The coupling of the trailing edge of pulse WS, for the certain period starting from trailing edge, is used for crystal of sampling
Transistor characteristic control signal Vb of pipe 125 declines.But, this does not comes into question.It addition, it is different
3rd embodiment to be described, for from initialize node ND121(primary nodal point) period
The certain period started, the transistor characteristic control signal for sampling transistor 125 increases.But,
This does not comes into question.
Subsidiary, the base electromotive force of sampling transistor 125 is fixed potential, and coupled voltages is not ideally
It is input to base voltage.It is additionally, since line resistance (the resistive element R that there are in fact backgateBG), institute
To be connected to the backgate terminal as transistor characteristic control terminal and control input when resistive element 622
Time between son, coupled voltages can be imported into backgate terminal, as in a second embodiment.
But, line resistance (the resistive element R of backgateBG) there is less resistance value, and may
There is the situation by the coupling of capacity cell 622 with less impact.That is, by capacity cell 622
With line resistance (=resistive element RBG) time constant that limits is less, and coupled voltages application time
Shorter.When increasing transistor characteristic control signal Vb at sampling periods and mobility correction period when starting
Period expectation when being lengthened to a certain degree, preferably by the transistor characteristic at sampling transistor 125
Control terminal and being used for applies to provide between transistor characteristic control signal Vb circuit resistive element 625
Form time constant adjustment member 624.Due to the insertion of resistive element 625, resistive element 625 He
Resistive element RBGBetween divide write pulse WS voltage.However, it is possible to improve by capacity cell 622
Line resistance=resistive element R with resistive element 625(and backgateBG) time constant that limits.Cause
This, can extend and increase transistor characteristic control signal Vb at sampling periods and mobility correction period when starting
Period.
[the 3rd embodiment]
Figure 16 and 17 is to illustrate the image element circuit 10C according to the 3rd embodiment and include image element circuit 10C
The figure of form of display device.There is in pixel array portion 102 pixel according to the 3rd embodiment
The display device of circuit 10C will be referred to as display device 1C according to the 3rd embodiment.Figure 16 illustrates (one
Individual pixel) essential structure.Figure 17 illustrates specific configuration (whole display device).Figure 18 illustrates help
Explaining the sequential chart of the operation of the 3rd embodiment, attention points to transistor characteristic control signal Vb.
As shown in Figure 16 and Figure 17, the 3rd embodiment has transistor in each image element circuit 10C
Characteristics Control part 620C.Transistor characteristic controls part 620C and has capacity cell 632, this electric capacity
Element 632 is connected to transistor characteristic control terminal (backgate terminal) and the conduct of sampling transistor 125
Between the video signal cable 106HS of video signal cable DTL.Characteristics Control sweep test 621 is not must
Must.Subsidiary, in figure 16 by resistive element RBGRepresent the line of the backgate of sampling transistor 125
Road resistance.Transistor characteristic control part 620C be may also include and applied by capacity cell 632 for adjustment
To the time constant adjustment member 634 of time constant of the signal of transistor characteristic control terminal, but time
Between constant adjustment member 634 not necessarily.As an example, time constant adjustment member 634 has electricity
Resistance element 635, this resistive element 635 is connected to the transistor characteristic control terminal of sampling transistor 125
And between the circuit applying transistor characteristic control signal Vb.In figure 16, resistive element 635
It is arranged between the backgate terminal of capacity cell 632 and sampling transistor 125.But, resistive element 635
May be provided between capacity cell 632 and video signal cable 106HS.
3rd embodiment has the structure similar with the second embodiment, the differ in that: the 3rd is real
Execute example to be regarded by the backgate and video signal cable DTL(that capacity cell 632 is added to sampling transistor 125
Frequently holding wire 106HS) between, and video signal V when writing a signal tosigThe coupled voltages of rising edge
It is input to base electromotive force, thus promotes by the sampling transistor 125 write to signal voltage.
As shown in Figure 18, it is coupled to by capacity cell 632 when the rising edge of the electromotive force of video signal cable
During backgate terminal, for from sampling periods and mobility correct the period start certain period, crystal
Pipe characteristic control signal Vb can increase.Therefore, the threshold voltage V of sampling transistor 125thChange to become
Lower, it is possible to promote by the sampling transistor 125 write to signal voltage.
Subsidiary, such as the second embodiment, also as in the 3rd embodiment, it is contemplated that the line resistance (electricity of backgate
Resistance element RBG) resistance value less, it is possible to provide the time similar to time constant adjustment member 624 is normal
Number adjustment member 634 extends the beginning increase transistor spy correcting the period at sampling periods and mobility
The period of property control signal Vb is to a certain extent.
In a second embodiment, constant transistor characteristic control signal Vb is applied to sampling transistor
The backgate terminal of 125, and unrelated with the amplitude of video signal.In the third embodiment, have corresponding to
Transistor characteristic control signal Vb of the size of the amplitude of video signal is applied to sampling transistor 125
Backgate terminal.That is, back-gate effect the luminance shortage phenomenon caused is according to video signal VsigAnd different,
And the 3rd embodiment can control the transistor characteristic in each image element circuit 10B when reflecting these difference
Control terminal.
[the 4th embodiment]
Figure 19 and 20 is to illustrate the image element circuit 10D according to the 4th embodiment and include this image element circuit
The figure of the form of the display device of 10D.Pixel array portion 102 has according to the 4th embodiment
The display device of image element circuit 10D will be referred to as display device 1D according to the 4th embodiment.Figure 19 shows
Go out (pixel) essential structure.Figure 20 illustrates specific configuration (whole display device).Figure 21 is
Helping explain the sequential chart of the operation of the 4th embodiment, attention points to transistor characteristic control signal Vb.
As shown in Figure 19 and Figure 20, the 4th embodiment has transistor in each image element circuit 10D
Characteristics Control part 620D.Transistor characteristic controls part 620D and has buffer (buffer) 642,
This buffer 642 be connected to sampling transistor 125 transistor characteristic control terminal (backgate terminal) and
Between control input terminal (gate terminal).Characteristics Control sweep test 621 is not necessarily.Subsidiary,
In Figure 19, by resistive element RBGRepresent the line resistance of the backgate terminal of sampling transistor 125.
Transistor characteristic controls part 620D and may also include amplitude adjustment member 644, this amplitude adjustment member 644
For adjusting transistor characteristic control signal Vb being applied to transistor characteristic control terminal, but amplitude is adjusted
It is not essential for for whole point 644.As an example, amplitude adjustment member 644 has resistive element 645,
This resistive element 645 is connected to transistor characteristic control terminal and the buffer 642 of sampling transistor 125
Between.Transistor characteristic controls part 620D and may also include pulse width adjustment member 646, this pulse width
Degree adjustment member 646 is for adjusting the transistor control signal Vb being applied to transistor characteristic control terminal
Pulse width, but pulse width adjustment member 646 is not essential for.As an example, pulse
Width adjustment loop 646 has differential (differentiating) circuit 647, for by buffer 642
Write pulse WS differential on input side.Be enough to form peaker by resistive element and capacity cell
647。
4th embodiment and the second embodiment similarity are to use the write pulse WS of time for writing signal.
But, the 4th embodiment is with the difference of the second embodiment: the 4th embodiment is essentially by buffering
Device 642 rather than coupled by the voltage of capacity cell, is input to sampling transistor 125 by write pulse WS
Base electromotive force, thus promote by the sampling transistor 125 write to signal voltage.Insertion amplitude adjusts
Part 644(resistive element 645) promote that the transistor being applied to the backgate terminal of sampling transistor 125 is special
The adjustment of the size of property control signal Vb, as shown in figure 21.Insert pulse width adjustment member 646(micro-
Parallel circuit 647) promote to be applied to the transistor control signal Vb of the backgate terminal of sampling transistor 125
The adjustment of pulse width Δ T, as shown in Figure 21.4th embodiment has than the second embodiment or
The circuit structure that three embodiments are more complicated, but promote the backgate end being applied to sampling transistor 125
The size of transistor characteristic control signal Vb of son and the adjustment of application time.
[the 5th embodiment]
Figure 22 A to 22E is to aid in explaining the figure of the 5th embodiment.5th embodiment is to include display device
The example of electronic installation, this display device applications is for suppressing or eliminating described above by carrying on the back
The technology of the luminance shortage phenomenon that matrix effect causes.The place of the suppression display inhomogeneities according to the present embodiment
Reason is applicable to display device, is included in the current drive-type display element that various electronic installation uses, this electricity
Sub-device such as game machine, e-book, electronic dictionary, mobile phone etc..
Such as, Figure 22 A shows that electronic installation 700 is to use showing of the example as image display device
Show the axonometric chart of the example of outward appearance in the case of the television set of module 704:.Television set 702 has setting
Display module 704 in the front surface of the front panel 703 supported by pedestal 706, and at display table
There is on face filtering glass 705.Figure 22 B is to illustrate the situation that electronic installation 700 is digital camera 712
In the figure of example of outward appearance.Digital camera 712 includes display module 714, controls switch 716 and fast
Door button 717 etc..Figure 22 C illustrate electronic installation 700 be in the case of video camera 722 outside
The figure of the example seen.Video camera 722 has the one-tenth for being imaged on the object before main body 723
As lens 725, and also include display module 724, for obtaining the beginning/shutdown switch 726 of image
Deng.Figure 22 D be electronic installation 700 be the figure of the outward appearance example in the case of computer 732.Computer
732 include downside shell 733a, upside shell 733b, display module 734, IP Camera 735, keyboard
736 etc..Figure 22 E is to illustrate that electronic installation 700 is the outward appearance example in the case of portable phone 742
Figure.Portable phone 742 is folded form.Portable phone 742 include upside shell 743a, downside shell 743b,
For hinge in display module 744a, sub-display 744b, photographic head 745, coupling part this example of 746(
Chain part), image lamp 747 etc..
By using the display device according to the present embodiment to manufacture display module 704, display module 714, show
Show module 724, display module 734, display module 744a and sub-display 744b.Therefore, each
Electronic installation 700 be possible not only to correct by drive the threshold voltage of transistor and mobility change (and
The change of k) and the brightness flop that causes, it is also possible to suppress or eliminate the brightness caused by back-gate effect
Not foot phenomenon, and can therefore realize the display of high image quality.
Below the embodiment in this specification has been used to describe the technology disclosed in this specification.But,
The technical scope of the content described in claim is not limited to the scope described in preceding embodiment.Can be to front
The embodiment in face does various changes and modifications, without departing from the spirit of technology disclosed in this specification,
And the form obtained by increasing this changes and improvements is also contained in the technology disclosed in this specification
Technical scope.Embodiment above is not limited to relate to the technology of claim, and is not in embodiment
The combination of all features described is all that the problem solving to be covered by the technology disclosed in this specification is musted
Must.Embodiment above includes the technology in each stage, and by combining multiple disclosure suitably
Detailing requiments can extract various technology.Even if when the possessive construction disclosed in the present embodiment requires
When omitting some detailing requiments, the structure omitting the generation of some detailing requiments also can be extracted as in this specification
Disclosed technology, as long as obtaining the effect of the problem corresponding to being covered by the technology disclosed in this specification
?.
Such as, about the luminance shortage phenomenon that caused by back-gate effect of elimination, it is possible to with would correspond to
The driving voltage of video signal is write the mode processing operation association of storage capacitor and is controlled write transistor
Characteristic is sufficient for, and it can be deployed in various structure, as long as can with the driving that would correspond to video signal
The mode of the process operation association that voltage writes storage capacitor controls the characteristic of write transistor.For
The component providing this is included in image element circuit not necessarily, and can be by by being arranged on picture
The Characteristics Control sweep test 621 in control part 109(the example above outside element circuit) design picture
The timing (difference with reference between first embodiment and the second to the 4th EXAMPLE Example) of element circuit 10
This offer is provided.
Selectively, do not providing independent Characteristics Control sweep test 621 in the outside of image element circuit 10,
Can exist constructed as below: this structure uses the driving arteries and veins exported by another sweep test by logic circuit
Punching produces the high/low scanning impulse corresponding to transistor characteristic control signal Vb, makes scanning impulse carry out
Level conversion, and then output has appropriate level Vb_HAnd Vb_LTransistor characteristic control signal
Vb。
It addition, in embodiment above and example, threshold voltage can be controlled when write transistor has
During transistor control terminals (such as backgate terminal etc.), transistor characteristic control terminal for with by right
The mode processing operation association of storage capacitor should be write in the driving voltage of video signal, control to write crystalline substance
The characteristic of body pipe.But, this is only example, and this technology is not limited to use transistor characteristic to control end
Son performs the structure controlled, as long as " certain period adjacent after writing beginning ", write transistor
Write capability increases.Self-evident, can select and supplement structure, such as n-raceway groove in supplementary structure
Transistor AND gate p-channel transistor exchanges, and the polarity of multiple electric power and signal inverts accordingly.
Explanation based on embodiment above, the technology relating to claim is example, and such as extracts
Techniques below.This technology is listed below.
[supplementary notes 1]
A kind of image element circuit includes:
Display part;
Storage capacitor;
Write transistor, writes described storage capacitor for would correspond to the driving voltage of video signal;With
And
Drive transistor, be used for, based on the driving voltage writing described storage capacitor, driving described display
Part;
Wherein can be to write described storage capacitor with the driving voltage that would correspond to described video signal
Process the mode of operation association, control the characteristic of described write transistor.
[supplementary notes 2]
According to the image element circuit described in supplementary notes 1, also include:
Characteristics Control part, it is configured to write institute with the driving voltage that would correspond to described video signal
State the mode processing operation association of storage capacitor, control the characteristic of described write transistor.
[supplementary notes 3]
According to the image element circuit described in supplementary notes 1 or 2,
The process of described storage capacitor is wherein write at the driving voltage that would correspond to described video signal
In period, increase the write capability of described write transistor.
[supplementary notes 4]
According to the image element circuit described in supplementary notes 3,
The process of described storage capacitor is wherein write with the driving voltage that would correspond to described video signal
The write capability of described write transistor is increased while beginning.
[supplementary notes 5]
According to the image element circuit described in supplementary notes 3,
The process of described storage capacitor is wherein write with the driving voltage that would correspond to described video signal
The threshold voltage of described write transistor is reduced while beginning.
[supplementary notes 6]
According to any one the described image element circuit in supplementary notes 1 to 5,
Wherein said write transistor has the Characteristics Control terminal that can control threshold voltage, and
Characteristics Control part is for being applied to described Characteristics Control by the control signal controlling described threshold voltage
Terminal.
[supplementary notes 7]
According to the image element circuit described in supplementary notes 6,
Wherein said write transistor is metal-oxide membranous type field-effect transistor.
[supplementary notes 8]
According to the image element circuit described in supplementary notes 6,
Wherein said write transistor is back of the body gate type thin film transistor.
[supplementary notes 9]
According to any one the described image element circuit in supplementary notes 6 to 8,
Wherein electric capacity unit is set between the Characteristics Control terminal and control electrode terminal of described write transistor
Part, the control applying the conduction/non-conduction for controlling described write transistor to described control electrode terminal is believed
Number.
[supplementary notes 10]
According to any one the described image element circuit in supplementary notes 6 to 8,
Wherein electricity is set at described Characteristics Control terminal with between the video signal cable transmitting video signal
Hold element.
[supplementary notes 11]
According to the image element circuit described in supplementary notes 10, also include:
Time constant adjustment member, it is constructed by the adjustment of described capacity cell and is applied to described characteristic control
The time constant of the signal of terminal processed.
[supplementary notes 12]
According to the image element circuit described in supplementary notes 11,
Wherein said time constant adjustment member has the resistive element being connected to described Characteristics Control terminal.
[supplementary notes 13]
According to any one the described image element circuit in supplementary notes 6 to 8,
Wherein the pulse corresponding to the control signal of the conduction/non-conduction for controlling described write transistor is believed
Number it is applied to described Characteristics Control terminal.
[supplementary notes 14]
According to supplementary notes 13 described in image element circuit, also include following at least one:
Pulse width adjustment member, it is configured to adjust for the conduction/non-conduction controlling described write transistor
The pulse width of control signal, and described control signal is applied to described Characteristics Control terminal, institute
State pulse width to be arranged in conducting state by described write transistor;And
Amplitude adjustment member, its amplitude being configured to adjust the signal being applied to described Characteristics Control terminal.
[supplementary notes 15]
According to any one the described image element circuit in supplementary notes 1 to 14, also include:
Pixel portion, arranges display element in described pixel portion,
The characteristic of the write transistor during wherein Characteristics Control part controls each display element.
[supplementary notes 16]
According to the image element circuit described in supplementary notes 15,
Wherein said pixel portion has the described display element arranged with two-dimensional matrix form.
[supplementary notes 17]
According to any one the described image element circuit in supplementary notes 1 to 16,
Wherein display element is emissive type.
[supplementary notes 18]
A kind of display device, including:
Multiple image element circuits, described image element circuit includes display part, storage capacitor, would correspond to regard
Frequently the driving voltage of signal writes the write transistor of described storage capacitor and for described based on writing
The driving voltage of storage capacitor drives the driving transistor of described display part, and described image element circuit is by cloth
Put;And
Characteristics Control part, it is configured to write institute with the driving voltage that would correspond to described video signal
State the mode processing operation association of storage capacitor, control the characteristic of described write transistor.
[supplementary notes 19]
A kind of electronic installation, including:
Multiple image element circuits, described image element circuit includes display part, stores capacitor, for by correspondence
Driving voltage in video signal writes the write transistor of described storage capacitor and for based on writing
The driving voltage of described storage capacitor drives the driving transistor of described display part, described image element circuit
It is arranged;
Signal generator divides, for producing the video signal being applied to described write transistor;And
Characteristics Control part, it is configured to write institute with the driving voltage that would correspond to described video signal
State the mode processing operation association of storage capacitor, control the characteristic of described write transistor.
[supplementary notes 20]
A kind of pixel circuit drive method driving image element circuit, described image element circuit includes for by correspondence
Driving voltage in video signal writes the write transistor of storage capacitor and for driving display part
Driving transistor, described driving method includes:
To write the process operation of described storage capacitor with the driving voltage that would correspond to described video signal
The mode of association, controls the characteristic of described write transistor.
The disclosure comprises the Japanese earlier patent application relating on June 8th, 2011 and submitting in Japan Office
Theme disclosed in JP 2011-128238, is herein incorporated entire contents by quoting.